Based on all of this discussion, I am leaning toward mixing and matching the two carbs I received, using the the carb body, main jet with the washer (and no emulsion tube), and the needle that came with it.  The higher quality slide will go into it as well.  This first carb body is not drilled for the upper vertical vent tubes, but has the horizontal ones.  As soon as I find a way (maybe using drill bits) I will try to measure the air bleeds on both.

Good stuff Sneeze!  Thanks for sharing!  I mis-spoke on one of our earlier posts/comments - I checked again and I actually ended up buying from 'usamotoking' for $37.19.  It compares more closely to the JFGRacing carb, but it has a straight 40mm bore on the spigot side (no tapering).  I didn't do any measuring on other items so I can't comment on those specifics.  Mine has the 2-piece main.  Needle jet resembles the one with 'less taper'.  The polish and finish on my carb is absolutely beautiful especially the slide and ports - you'd approve for sure - it's even better than the JFG in your pic.  Mine also came with the #50 and #170 installed.  With DragBikeMike's expertise, I am very happy with the re-jetting at #35 and #140 (stock bike at sea level).  

Right now, my only 2 complaints about my PWK40 carb are:

1) it weeps a tiny amount of gas at the air/fuel mix screw when you hit about 3 turns out - not a huge deal for me as I aim to tune to 1.5-2.0 turns out, but I would expect 3 turns out to be okay (problem in the future? we'll see).  My mix screw is soft brass and not plastic.  

2) there is no float bowl drain drain/tube (not a huge deal).

My only slight performance problem/tuning question is that the bike idles very low when the engine is cold.  It actually stalled once when I didn't keep my hand on the throttle long enough - I have hold it's hand for at least 30 seconds or it will stall.  Once warned up to efficient operating temperature it's great.  I know this is a normal dynamic of a carbureted internal combustion engine, but its very noticeable with this carb or my set-up.  Related side note: If I use the choke, the bike dies almost instantly if I don't return the choke to normal position within 2-3 seconds and then I still have to hold the throttle for like 30 seconds.  It's getting cooler here now, so I'll get a better sense of the choke behavior in the coming months.  I've tried tuning this out by playing with the air/fuel mix, but really not accomplishing anything and I like my air/fuel mix tune when its warm and I really don't want to foul that up.  Any expertise and advice here would be greatly appreciated.  FYI - mine came with the e-clip in the 2nd notch from the bottom - I left it there (one notch to the rich side).  I'm wondering if bumping the e-clip up to the middle notch (leaner) might address this issue - seems logical to me - it's like I'm too rich at cold idle, too rich with choke, but runs great when warned up... (thoughts?)

I have several things to rule out before I completely blame the carb or my tuning - 1) valve lash adjustment (it's too noisy up top), 2) new battery (I'm at my minimum acceptable fully charged level of 12.6 volts), 3) check my spark plug for evidence of lean/rich condition.

Also, I just swapped out the stock muffler for a Dyna muffler this weekend.  It sounds soooo much better.  I didn't re-jet and the 35 seems fine (I'm at about 2.5 turns out on the air/fuel mix).  I haven't tested at WOT so I may need to bump up a size on the main jet to a #142 or #145 to optimize rpm horsepower.  I will probably go ahead and bump up to the #38 primary jet and move the e-clip up to the center notch when I do the valve lash adjustment while I already have the gas tank off.  I'm not doing any WOT testing until I get the valves adjusted and look at the spark plug.

I know I should probably do one tweak/modification at a time, but I'm an impatient 'chef' that prefers messy scrambled eggs over pretty omelets.

FWIW, I got the JFG PWK38 with #170 & #50 jets, and though I haven't done much testing (just a few short rides), it is 100% better then the stock carb and runs great on out of the box jetting   Just to add more confusion! Only mod is Ryca kit, slip on, and pod intake.

Back in the day my best friend had a Kawasaki H1 triple with tuned chambers.  OMG!!!  Faster than believable, with a rubber frame between the wheels.  Went crazy fast in a straight line and scared the crap out of you in the corners.

Online you never know the level of someone's experience unless they bring it up first.  And like all the people on here, just trying to help.  I would have verified the same thing, btw.  Make sure it's not a dead motor.

Update on my PWK40.  Rejetted to #38 primary and #155 Main.  Performed valve lash adjustment (need to try again to hit perfection, ticky ticky...), adjusted decomp solenoid cable free play to 4mm (it was way off, like 7+mm, and it was sticking too).  My weird random top end noise is gone after adjusting. I'm 99% sure my noise was due to the sticky decomp and cable free play out of spec..

I am extremely impressed with performance!  This bike rips now!  Clean idle, smooth power, throttle response is sweet, no bogs, no lags, no after fire kaboomers just a little crackle...  I'm at 1.5 turns out on the air/fuel mix screw with the side cover removed on the air box.  Time to call this a sweet success experiment!!  

Now back to the valve lash...  When you are at TDC on the compression stroke, how much wiggle (free play) should I expect on the rocker arms?  I had very little and not easy to wiggle.  Are the timing marks sometimes not 100% accurate (am I cockeyed maybe?)?  I had the bike on the stand and leaning and I'm laying on the floor wearing my bi-focals.  I'm 99% sure I was spot on the marks...  Thoughts/Experience anybody?  And what a pain getting feeler gauges in there (no room to work...)