Heard of it being done, but they won't seal worth a sh**.
Heck, Direct Connection used to sell head spacers to drop your compression, back in the bad old days of the first couple of "gas crises". Didn't last worth a hoot then, they dropped them pretty quick.
Plus, once you start stacking, or using spacers, or whatever- you start messing up your intake port alignment, so you have to stack intake gaskets to compensate, and it just snowballs to the point where nothing fits right and everything leaks...
