Hi,
this is a fairly easy swap, motor mounts will all work, trans will bolt up fine, you can use the same converter but you'll have to weld balance weights on it cause the 76 motor is a cast crank and externally balanced, if you have the converter that came with the 440 you can knock the weight off and weld them on, not as hard as it sounds, you can't swap the late model converter in the 63 trans cause the input splines are different, everything else will work fine, use the water pump housing from the 383 so the radiator hoses match up. any other questions pm me.
Russ