I would back down a little with iron heads, closer to 9.5:1. Here's a forged piston from KB that will produce a 9.6:1 SCR with 64cc heads.
Notice the compression height on these pistons is 1.433", 0.008" taller than most 383 pistons that measure 1.425". This additional compression height will get the piston crown closer to the block deck at TDC and should make it easier to adjust your SCR and squish.
Choose a cam that closes the intake at ~35 degrees ABDC @0.050" tappet lift for a dynamic compression ratio of 8.49:1 that will operate on pump gas.pisto