It's not so much that I know a lot about them, I just know where to go to find the info that's needed.
And that comes from hanging around here for years.
I'm not sure what the valve sizes are on the B12, but they're all the same size, regardless of year. All Bandits are screw & locknut style, like the early GSXR's and not the shim type like the 91-92 GSXR1100 & 91 GSXR750.
There's a lot of interchangeabilty between the SACS family of engines. For details of what swaps, go to
http://www.oldskoolsuzuki.info/ and click on the "Seven-Eleven" link in the upper left margin, then scroll halfway down the new page and click on "Frankenstein's Guide to Oil Cooled Monsters". I'd post a link to take you directly there, but their site won't work that way.
According to Franky, the B12 has the same size valves as the 1127 and 750R, but he doesn't say what that size is.