Replacing Head Gaskets Today, Need INFO

Alright, My 88 Cutlass started leaking coolant from the back of the engine, I preasurized then system, and got under the car, and sure enough it was spraying out of the head gasket.
Im starting to tear it all apart later on today.

My question is the car has 127,000 miles on it, when I check the heads and intake for flatness with a straight edge, and feeler gauge does anyone know what the acceptable limit is, ive heard around .002-.006 is ok, but im sure all cars are different.. Anyone know what GM says about this?

Thanks in advance...

002-003 is the max on the deck and heads.