I know this because it's in the Chrysler engine book and I've done it many times. Well, the amount to mill off isn't but the deck thicknesses are.
The OE passenger car stuff has about .500 thick decks. You can take .100 off of that. If you take more yo can compromise head gasket sealing but the Chrysler stuff can go a bit thinner than a Chevy deck because Chrysler used blind head bolt holes and the head bolt holes are supported by bracing under the deck. Bracing for lack of a better term.
The X blocks have a .750 thick deck and the R blocks are 1.00 thick.
I disagree with the argument that compression ratio changes make little difference. It might not make much difference on a dyno, but in the car it's a big difference in drivability. You don't see that on most engine dyno's. Compression ratio increases also increases expansion ratio. That's also a big deal because it affects blowdown and helps reduce pumping losses.