This is how I figure it! :
The 400 Chev would wear out the bores alot quicker than the other standard production motors because of the short rod length. I will try to explain three different options to build a 383 :

The stock 400 small block chev crank turned down to 350 chevy main bearing size, you have the stock counterweight and you will have to use the stock chevy short rod because the crankshaft is counterweighted for the short rod.

Eagle crankshafts: For the 383 you can buy either cast steel or forged steel. The crankshaft will drop straight into the 350 block also they have the larger counterweights so that yuou can run the standard 5.7in rod or the better eagle 5.7in steel rod which are claimed to handle up to 600hp. For the camshaft clearancing problems you can use the 12point connecting rod nuts and a little bit of clearancing on the side shoulder of the rod, this does not weaken the rod in any way. As far as I am aware this setup is externally balanced.

Scat crankshafts: There is a big choice with these crankshafts. They have bigger counterweights to use the 5.7in stock length rod as explained above and externally balanced in one option. Another option they offer is aninternally balanced setup were you use the standard torsional vibration damper and flywheel. These cranks have massive central counterweights. These also come with the option of cast or forged steel.

The advantage of using the last two cranks is they are brand new and not wornout and they have nicely radiused bearing journals and oil holes.