383 piston choice

If the motor is setup with quench it can be done , I did it with a 440 with KB quench dome pistons and off the shelf Comp cam , 10.3 compression runs fine on 93 octane. this build was a copy of a build another guy did , I did this for a friend , the other build is only 9.3 , not good quench and more head Cc and it will not run on anything less than 93 , something is not right with that build in my opinion.

He's not going to do it with 906's without a custom piston and a lot of machine work .

The KB400 is probably the piston to use , will get you over 9.0 compression and give you a huge valve relief to clear a bigger cam, also there are much better cam choices now than the MP .484 cam.

The only stock rod aftermarket for the 383 is the eagle rod , BUT i am not sure is the
KB piston is setup for pin locks which you will need because the eagle is a floating pin rod .

Diamond sells a piston that has valve reliefs but it's a 1.916 CH , a little short and it's not cheap but for a little more you can get the pin height moved so less machining will need to be done in the big picture .