I have just done this swap in my 54' 3100 actually! Completely rebuilt the 292 from top to bottom with some moderate upgrades! Feel free to message me for details!
It's been years since the 235 was in this truck so I don't quite remember how it sat, but the water pump/fan does seem to be lower on the radiator (I haven't lowered my radiator....yet?). Some 292's had bypass hoses on the drivers side from the water pump to the thermostat housing, but you can delete this if desired from what I've been told.
As far as the differences between the 75-77 and 78-86, other than mild differences in water pump styles... I honestly don't know so I'll let others chime in here that are more knowledgeable than myself. My 292 is from 1966 I believe.
GMJager, can you tell me how the 750 carburetor with the 12bolt kit is working for you? Would you stick with it or go another route if you had to do it again?
Thanks,
Eric
