Clutch Issues

[twoskies]

Hi

ive got a 1972 c10, from the factory it had a 350/4 bolt main with a muncie sm465 4 speed(pretty common) before i got it someone had stuck a 305 in it, it was junk, i pulled that motor asap, found a 350/4 bolt main out of a 1979 el camino ,10,000 miles, was going to put motor in today, found out the pressure plate would not fit, too small on the crank diameter, started measuring the clutch and pressure plate about 12 inches in diameter, checking with the parts stores they are telling me the diameter should be 14 inches, any help appreciated
also if anyone has factory parts numbers


also could the bell housing need changed or is it the same

i can look up numbers (id) if anyone tells me where to look


thanks