Eww That's nasty! Worst carbs I've ever seen...
Let's see when I ear shaved mine, I called Sudco and gave the guy the part numbers and they mailed them to me. I did some shopping around, researched how other guys did it and sudco was the cheapest place I could find, and the parts I received were quality. Here's the info you'll need.
1 Mikuni (Sudco) Needle Shims Item# 009-396 $7.95
2 Keihin PN: 99101-393 Main Jet Size: 142 $13.90
2 Keihin PN: N424-22 Pilot/Slow Jet Size: 42 $13.90
Double check that those are the right numbers by entering them on Sudco.com
As for the O-rings, I can't say for sure that Ace will have what you need, each one is different. I would take a trip down there and see though. I just replaced an O-ring for the final drive and found one that matched up perfectly from Ace. However, for the ear shave I ordered mine off Ebay I believe.
1990 VN750 Red and Black
Bought on 6/30/2012 w/ 13,230 miles
To Do List: Paint Front Rim, Acct- mcct mod
Done: Adjusted Float Bowls, R/R Replace and Relocate, Coastered, Ear Shave, Front/Rear Tire Change, Replaced Final Gear Seals, Splines Lubed, Relay Coil Mod, Replaced Fork Seals, Rebuilt Starter