Yes the heads and head gaskets play a huge part in your compression. What I was meaning by the cam having something to do with compression is not in the final comp ratio but in how that compression is put to use. If you have a high duration high lift cam that will allow more air into the engine thus giving you a bigger bang correct... Well if your compression is too high that bang will not be able to be used as well since the timing will not be able to be as far advanced to prevent detonation. Now if you lower that comp to say 9.5:1 instead of 10:1 you get a little longer time to burn, a little more room for the burn and you should be able to run a higher advance to allow more time and get the full power out of that one stroke.

Part of building a good performance engine is not just throwing the best of the best and the biggest of the big in the engine and be good. It is about making sure that everything works smoothly together, the engine is built with the durability needed to handle the work it will be doing, and the rest of the equipment in the engine is all tuned together. This is all called Blueprinting an engine. Doing things like making sure every ring has the same and correct gap, each piston assy is exactly the same weight, the rotating assy is balanced, all clearances have been checked and heat expansion is accounted for. This is all part of the process.

Massey