Looks like you've got yourself a 305. 83.5 cc's is way big for a combustion chamber on that motor. 58 was stock. I believe you forgot to take into account the dish in the pistons, the volume added by the head gasket, and the volume created by the piston not travelling all of the way to the top of the cylinder (deck clearance .025" on a stock motor).

Any head you buy is going to have larger combustion chambers as they are all designed with the 350 in mind and will have combustion chambers ranging from 64-76 cc's. That will drop your compression rato significantly. If you were to put flat top pistons in and use the 64 cc heads, that would bump your compression ratio to 9.1:1 which is a good start. After that, you can put in some thinner head gaskets of .015" to .020" which will put you between 9.6 and 9.7:1 and help squish. Not bad. The only concern is will the 1.94" and 1.5" valves fit in your cylinders.