I have a rebuilt 305 TPI that runs strong. But heads are just ported stock units. I have a pair 113 casting aluminum corvette heads that have been worked over that I would like put on the engine but I need to know if I can use a 305 head gasket or if I need to use a 350 head gasket. the heads are both 58cc but the 113's are 1.94/ 1.5 and the stock heads are 1.8/ 1.5. wich head gasket is needed?

 

It won't really matter, the 305 head gasket still isn't too small to hang over the bore of the block (obviously) or the heads. Choose the right gasket to keep your CR and quench where you want it.
MWnova runs those heads on his 305, you can ask him what he used.