Found this 383 thread May as well throw a few bones in for some members to chew

There are a number of ways of building a 383 short block

1 stock 400 crank..... lot of work , 1st machine down main bearings and you are restricted to the 400 short rod which is only 5.565 i Aftrernches long because the crank is balanced to the short rods. Crank is cast iron and it is quite old now

2 Aftermarket cranks, steel, and they are balanced for the longer 5.7 or 6.00 inch rods, due to the heavyer steel they can be internally balanced, so they are stiffer and have less tendency to flex

3 These aftermarket cranks can either be bought as an internal or externally banced option.

4 So when you buy the crank, buy it as a kit so you get the new pistons and new rods with the good ARP bolts, you usually have a choice with either I beam or H beam rods