Sorry for the tardy reply, been a long year... But thought I'd offer some notes.
The back of the block will bolt right in, but the front is a different matter. Make sure the 240 motor is complete, as you will need to bring over all the new style accessories with the motor, then find a 140 donor for the radiator and it's bracket. And make sure we are dealing with a Super C vs a straight C or the grill will be to short. Match the air cleaner to which manifold you use as they align differently.
I've done this swap before, it's possible; but the motors are not a direct swap. As Jim mentioned, the blocks are different which requires a new water pump and pulley arrangement. Everything is driven from a single thin belt vs the two belts used on the Super C. The upper water neck and the radiator inlet are also at different angles which requires the 140 radiator replacement.