OK on just a clean up. Got it.
The concern over the compression is very real. The fact that you are presently OK with 93 octane with the current open chamber heads does not mean at all that you will be OK with these closed chamber heads. You will be lowering the chamber volume by about 10 cc's. As an example, your SCR could go from 9.4 to 10.4, and it could be very touchy for avoiding detonation, unless the cam is moderately large and you are a good tuner. So you can't just blithely conclude you will be OK based on the present heads' performance.
Don't take this as a criticism at all; you are looking at a great set of heads. We just want to help steer you away from very possible trouble.
Just to help move this along, do you have the PN on that .510" lift Racer Brown cam? Or the cranking pressure as suggested?