360 compression

Factory steel shim head gaskets were about .020 compressed thickness. And according to:
I got specs for Felpro Head gasket 8553pt.
The Fel-Pro 8553 ranges anywhere from .046-.057 uncompressed, with the compressed figure being .003-.004 under that.
That means you would have to pay to have anywhere from .023-.034 milled off your heads to maintain your 8.7:1 compression ratio.
Machine work ain't cheap, so unless you're married to those gaskets I'd just get a pair of Mr. Gasket 1121G (.028 compressed thickness) to get you back in the ballpark.
But remember, it ain't just the head surface that will need to be milled- you'll need to either have the intake surfaces of the heads or the intake manifold gasket surfaces cut too, just to keep everything lined up. So you'll be paying for a minimum of four cuts, not just two.

*Edit- @Syleng1 's suggested .040 cut ain't a bad idea if you're having them cut anyways- a little extra compression at that low of a CR is a good thing.*