82 kz650 CSR petcock on a 78 kz650 B2

Has anyone ever taken a good look at the petcock from a 78 kz650, and determined if it could be converted to a non vacuum, on, off, and reserve type petcock ??

Also, is there anything that could be used to plug off a fuel hole in a petcock, that would withstand constant contact with fuel, and that wouldn't degrade over time ??

I'm going to take a good look at my 78's petcock to see if it could be altered to work as I want. I'm doing this for entertainment purposes, and to satisfy my curiosity. I think I've found a new replacement petcock that will work as I want. If I get no where with my 78's petcock, I'll be buying one.