Re: Original '67 350 rebuild...
I would recommend the 268H cam or the old L79 cam. The double hump heads have too small of intake ports to handle the port velocity that the newer cams create. I also agree that the larger valves are overkill. My engine builder wouldn't even install them in my double humps, as he had to many heads crack from the intake valve to the exhaust valve. "not enough meat" is what he said. You should have 10:1 (9.7:1) compression with the double humps and flat top pistons. He might be thinking of decking the block and using a shim head gasket, to boost your compression more.
I personally don't like decking the block anymore than you need to, to "true" it up. That's the same as boring the block to the max. If you have any future problems, the block is junk.
69 Camaro -originally a LM1 car. 327, Edelbrock E-streets, hooker, DUI performance distributors, ultradyne cam, stewart, TRW etc. Vintage Air, AGR steering, Corbeau GTSII seats, 700R4 transmission, 12-bolt w/Eaton 4.11:1