Kare,
I'm seeing this thread a little late as I've been too busy to be following the
"board" recently. So not really sure what the head issue is.
Is it that you think you might need an F head for an 8.7 CR and can't find one?
Part of the low CR from the F head is from the thick .047 head gasket used with it. Use it with the same .030 gasket as some of the other heads and the CR's are more similar, so a B20B head listed on an engine as 9.5 CR with the thin gasket is not all that much different.

Unless you plan to build this engine from scratch, I would suggest keeping things as simple as possible until you have the basic turbo concept done. Keep the compression ratio below 9.5 - 1, and use timing controls, including knock sensing, that can be done on an easy bolt on basis, to take care of detonation as long as the boost is kept within reasonable levels - say 6 - 8 lbs. to start off. Make sure the timing and air/fuel are OK, don't push the engine so hard you overheat things, and you should be OK with stock pistons. If I had a running engine, I would put the turbo system on that engine, make sure it worked, and not bother rebuilding it until problems ( broken rings, pistons, blowby etc.), results, testing, showed that to be necessary. When you get to that point, then worry about the best way to upgrade the engine so it will take higher boost.

Depending on which head you end up using, you might want to modify the exhaust port for better flow. Keep the intake stock. Make sure it has hardened exhaust seats.

I also agree with John on the bore/displacement issue. Don't spend money trying to get extra displacement on a boosted engine. A 5 - 10% increase in displacement is meaningless, especially when it is done at the expense of strength. For a turbo or supercharged engine you want to end up with a wall of
.150". Many B20 blocks have spots in the cylinder walls that are not any thicker than that to start with.

Hope this helps. Now back to head porting.

John
V-performance.com