early 273 pistons.

Hey Pishta, I just ran some numbers on this, and with .040" thick head gaskets, 62 cc chambers, and estimating about 8 cc's volume in the eyebrows plus in the ring around the perimeter, I come up with a static CR of 7.92. Even with .022" thick head gaskets, the SCR is 8.25.

So this does look to be the (a) lower compression combination. If it is tight, it may be just right for your turbo setup.

That all falls out of the pin height and the standard rod length, 1/2 of the stroke, and standard deck height. I can look at a stock 2 BBL '68 piston if you like.
The 273's had steel shim head gaskets. I imagine the compressed thickness to be .020 so the advertised 8/1 or 8.5/1 compression ratio is pretty close to the truth.