screamnz

I just purchased an 1977 xs400 for $75. Over all it is in good shape, except the carbs. The last time it was on the road was in 2003. The owner pulled off the carbs and put them on the shelf until now. The carbs are frozen, I cant get the butterfly valves lose. I have been looking for a new set of carbs, but all I can find are carbs for the xs650's. Does any one know if these will work on a 400? Also I would like if possible to switch from CV carbs to slide carbs. Does anyone know if the RD carbs will fit?