You can use stock 350 pistons in a 383 if you use 400 rods. The pin height is the same on 400 and 350 pistons. The 400 rods are shorter to compensate. Also, the rod bolts are countersunk on the 400 rods to help eliminate bolt to cam clearance issues.

The 383 in my 46 was built this way. It went together almost as easy as a stock engine. the only clearance problems was on the bottom of the piston skirt, none in the block.

If you're not going for high RPM's the short rods do OK. I had ARP rod bolts installed just for a little extra strength. I have my rev limiter set a 6000.

Mike