depends.....

most kits nowadays are made for the 5.7 rod and 6.0 rod.....some very well will posibly have camshaft interference...If so the you will need to use a small base circle cam....

The crank , if a 400 stock crank will have to be turned down to fit the 350 mains....

there are various companies that make a crank cast with 350 main spec's at the 3.75 stroke...

If I were doing a 383 I would buy the complete bottom end kit. It will be cheaper in the long run and you wont have to worry about mismatched parts....you will still have to machine the block to accept the 383 crank...Kits come in any piston/rod combo you like...