You will NEED to bearuette it first to check the chamber volumes, it could have had a big skim already.

No good copying what someone else did when their head could of been unskimmed to begin with and yours might already be down 40 thou.

also you need to set the CR up specific to the cam if you are doing it properly, the hotter the cam the more CR you can get away with, so you need to make a final decision on that first too.