What rear end do you have in your truck?
Will you use the original enclosed drive-shaft torque-tube?

Will you stay 6v?

If yes, any high-pressure 235 (1954 and later) or any 261 can "bolt right up", using the 1950 clutch housing, flywheel, and clutch assembly.

You would need to install Pre '68 Dave's water-pump adapter plate and your old water pump (to line up properly to your radiator)