Mix up the oil. put that side up, fill up to the shoulder. Let it soak. No way risking needing to drill is worth it. Patience..
A screwdriver, in the slot, and a few light quick taps every so often, shake it up, Not pounding it, it's brass and fine threads, not even a hammer, a small driver and an end wrench.. 9/16ths ish. Don't get harsh, induce vibration, while the penetrating oil is in it. Sometimes turning a stuck screw both ways helps. A bit of heat, doesn't require a torch, a soldering iron, even a blow dryer, anything to get those dissimilar metals to shift relative to one another. A squirt  bottle with water to cool it, quickly, can cause crud to be crushed and release. Heat and cool may be needed more than one time. The time spent Not needing to drill is well worth it.
A proper fit in the screw is crucial. Just because a screwdriver goes in doesn't make it a good fit. Does it go to the bottom of the slot?
You've got a screw. Get the one from the other carb. Put the screwdriver in, hold it up to the light and see how well it fits. If it's tapered, it wants to
Cam out.
Shape the tip to do the job. Any brass displaced by the slippage of the screwdriver can gently be put back in place using a pin punch and a very careful eye and hand. I'm speaking from experience,  not just pulling stuff out of my hat.

Lowe's sell a butane power soldering pencil for about ten bucks.
Removing the soldering tip exposes a small but intense , blue, pointed, flame. Remember, that's aluminium. Heat is like Brylcream.
A little dab'l do ya,,
And, you'll have a portable, no cord required, soldering tool.

Did you take the other screw and test the screwdriver profile?
WD40? Naaah, not where failure carries such consequences..

http://rivperformance.editboard.com/t7128-penetrating-oil-comparison-test

As soon as you figure out that the collective knowledge on this board is something you can use to win with, you'll be ahead.

I have a shelf dedicated to lubricants, and no WD40 even in my shop.
It's good for Water Displacement, and it's the fortieth formulation the guy tried, but it's not the best penetrating oil.

I tested the screw when i intially put the screwdriver in the bit to see if i could turn it. I also swapped it out for one with a better grip. The size is 1/4 which is also what I'd found when searching for a tools list online.

How do I find the members map?
And also, my first post was vague. I meant, i tested the screwdriver on the screw in the older carb to be sure of it's size. I later switched it out for one of the same size but with a better grip. When i pushed down firmly after having let it sit about an hr in wd, it turned easily. I hesitated after the second full turn and went back to read the instructions. When i tried again it only budged slightly but slipped the head again. It wouldn't budge when I tried again and so, i stopped. The screwdriver bit fit but it def wore around the tunnel heading into the screw. Tried to post a pic. I contacted the mechanic in Callao again. My problem has consistently been flakes and people wanting to tinker. I am desperate to get home before the winter chill sets in which is why i'm attempting it myself. I'm a voracious reader and I love my bike. I managed to drill the pilot hole and pull the plug never having used a drill. Have a little faith in me, i have faith in youbguys.

Looks like she is about 40 miles NE of Richmond, VA. Anyone in the area?

I dont know squat about carbs or I would let her mail it to me for a quick overhaul....anyone else have any ideas? A young lady who doesnt even have any experience with a hand drill....she may be in over her head here.

Alright, I have a full toolbox, carn cleaner, and a spare carb and petcock. I have hose caps also but that's about it. I have a Lowes, Autozone, and Adv. Auto Parts within driving distance and can purchase or rent anything else. I have access to a full garage w compression tester, torches, etc but it is the garage from which I just removed my bike and I'd prefer not to leave it there again. I also have a drill.

Never worked on a bike before, soent a LOT of time in the garage with my last Savage watching and learning the known issues. Used to tinker with my 78 Nova and do some light engineer work on boats (first mate)so I have a basic understanding of engines.
Still unable to download the manual from manualmadness and couldn't locate the other thread mentioned.

I can move the bike if there is someone nearby that can help but I have been looking for months. The shop Rick's in Callao hasn't called back since last wk. I have nothing but time and am super ready to go. The coming stotm may stall my work efforts a bit.
The idle mix screw is sitting at 1.5 turns. Should i turn it 3 full turns or rather 1.5 turn still and then back out 1.5 turn or should i attempt to get ot started now?

Maaan, I was just smiling, then I saw

Yes, my only transportation.

Awwrite, you're gonna be okay..

I'm not sure yet just what you accomplished with the air mix screw.
You got it out? Blast the hole? If the carb is off, I'd look at the jets,, you Might be able to do that with it mounted, if the screws have been out.
Those aren't#2 Philips, but if you can grind the tip down till the X fills up the screw slots.
If you have any fingernail polish remover you can mix it with transmission fluid, or, I dunno, maybe power steering fluid, but, next time in town, IF you can, a quart of acetone and you'll be able to refill the nail polish remover for a year.
A Zoom oil container is what I use for the penetrating oil, I keep it fully extended and capped, still some evaporation, but, since it separates, you can see when to add.

Okay, rundown what is done, and don't sweat a compression test.

Is the vacuum port on the carb plugged?

The carb is on, I'd try to fire it up.

You're up to speed on the battery, I expect.
Oil is good,, kick the tires, throw a leg over,stand it up..
See what happens..
Turn the gas on..