I would use a Silv-O- lite in a stock 350 only. Not a 383 or a 400.I tried it one time in a boat. Little too much timing, detonation, cheap piston, same results you had .Piston exploded.Use a forged piston and get the TBI figured out before You go through another one. You're out of wiggle room.Buy the pistons first and then have the block bored to the pistons using manufactors piston to wall clearance specs.If that doesnt work can the block and start all over.In the end thats going to be a very expensive 383. Hope the next one works out for you.P.S. Make sure You or the machinist mike each piston and each cylinder wall all the way down.