Depends on what gaskets are in there now. The standard Felpro gaskets that come in the engine kits are typically .054". The Felpro performance gaskets are .039". If you have the stock '72 pistons in there they have a reduced comression height so the thinner .025" gasket would help assuming you have thicker gaskers on there now. You can punch some numbers in here:
I doubt they'll raise it much. Maybe a half point max. Like Bill said the 72's had the pistons dropped down in the holes a bunch compared to the earlier ones.
thanks i havent took heads off yet i am going considering my options without going in bottom in though i might change the pistons but i need to see what i got first but thanks again for valuble information