Part of what you may be seeing and is probably throwing you off is the #$&%^*@#!! residue left by those craptastic felpro gaskets. That stuff is a nightmare to clean up, it leaves a coating in chunks that is a major bear to get off of there and you may spend a day or so cleaning it all off. That's why you are getting light under teh razor blade. Chances are the last head gasket install was laid down on top of existing residue leading to the buildup you have there and the gaps. Get it all thoroughly cleaned off before making any decisions. If once you get it ALL thoroughly cleaned if its flat with just minor pitting , go with it, if it's heavy enough to truely have a gap once you lay a straight edge on it, it will need to be decked
Once you get it cleaned off and run a bottom tap down the holes in the block, get a set of Victor Reinz head gaskets and shoot them down with about 3 light coats of
spray Hylomar on each side ( you'll need about 3 or so of those size cans )