Yes a 383 was originally built with a 400 3.75" stroke crank with the main journals machined down to fit in a 350 block. Then you had your choice of what rod length and piston combo you wanted to use. Before that the 377 was another combination, where you put a 350 crank in a 400 block. The 377 was a little more desirable early on as a race engine because you could put a forged 350 crank in the engine. No one wanted to build a HP engine with a cast crank so the 383 was not really seen as a race engine. Later on when aftermarket cranks were available the 383 took over.
