If I was going to use those brake calipers - I would take them apart and clean them up before I put them to use.  I would likely also buy the rubber seals and replace them......they get hard over time and the pistons can stick and cause the brakes to drag.

Clean the rubber parts with dish washing soap and hot water......no mineral solvents as the rubber can absorb it and the parts will be ruined.

The metal parts can be cleaned more aggressively with stronger soap and a cleaner......I would use Bike Bright as it is a strong cleaner/degreaser that does not attack paint or aluminum.  Pressure washing is fine once you have the caliper apart.  The "crud" you are talking about may be corrosion, as some of the brake dust can be corrosive to aluminum.  The only way to get that off may be to use steel wool, sandpaper, Scotch Bright, etc......follow up with fine steel wool and then polishing past (If you have a buffer - "Bob's your Uncle").

If you can't get the metal to look good - powder coating or brake caliper paint is your best best.

And Batman makes a good point - the stock master cylinder is sized for a single piston caliper on a single brake disc.  You should compare the size of the Savage caliper piston to the size of the caliper piston the brakes came from.....maybe even use the brake caliper that matches the front end you are using.  The Savage isn't powerful enough, heavy enough or fast enough to need dual front brakes - as good single disc will provide plenty of brake....but since you got 2 you might as well try it. 

Can someone tell me what's the preferred method of fork removal?
Do I take off the gas tank and hook ratcheting straps between the frame and the overhead joist in the garage to lift the front of the bike high enough?

You probably should take the tank off no matter what you do.
lift the front end your preferred method.
I have a chain hoist, and the hook goes in the square tube and you can lift the whole bike from there, nearly balanced.
jack stands under the front pegs works really well for the front end
or a block under the frame will do.

Ok found another set of calipers. This time they're tested good according to the seller. Ordered them and just got notified that they've shipped. That's quick!
No local hardware stores have chain hoists in stock. So I had to settle for a 2 ton come-along.
https://www.acehardware.com/departments/hardware/chain-and-rope/load-binders/...

It'll work fine just to lift the front up.
I'll get it setup when it cools off later.

Harbor Freight is in the shoot-your-way-in-shoot-your-way-out side of the county. Not in the mood to ride through there today and can't remember where my bulletproof vest is.

I used a Come-Along to hoist the bike in the shop and set it down on a cinder block. I used a thin wooden shim to make it solid. While I was doing things that could upset it I kept the hoist connected and just barely snug.
That was enough to get the seals done.
I'd pull the tank if I was messing with the crown nut. Be a shame to mess it up.

I have a strap, very heavy thing, on a 2x12 the Come-Along is on, and some woven nylon rope I put on the bike.
It's not cheap. If the rope you're looking at has a woven exterior and strands of something running inside that woven tube, don't.

Borrowed my neighbors chain hoist. The come-along was too long.