These engines are 10:1 CR so you consider 8# about the max you can go without running 100+ octane or methanol injection.

Also keep the timing short like 22* total under cruise and 8-10* under boost.

If you want to run more boost - well time for pistons and rods.

51 GMC 4.2 turbo
Can't solved today's problems using the same technology/thinking that created them