That KB piston is a piece of garbage , it's .024 in the hole on a factory blueprint block and it has HUGE valve reliefs , at zero deck you need a head under 80cc to get any compression out of it.
The speedpro forged is better , but still too deep for my taste.
The best piston would be a Diamond , square deck your block then give the deck height to a Diamond WD and ask them to do a semi custom on the shelf stock , change the CH to get the piston at zero , or .015 above the deck if you are using an open chamber head, and add their std 4cc valve relief . Use this with an 80 cc head and a steel shim gasket and get a vey close to 10.0 compression .
It's hard to get a decent compression ratio with a 383 because of the small bore and short stroke .