oh, okay, that makes sense. :-)
I dont think you need to worry about the 800 unit being too big... remember all electronic Qjets where 800 units ( for all I know ) and they came on small engines, like 305, 307, 350.
Heck, the pontiac 301 came with an 800 unit.
I have had luck drilling seized pieces of throttle plates screw out and installing new screws no problem.
btw, are you sure you are not doing the damage over againg by soaking this carb in laquer thinner also?