Thanks for the information on the Comp 268H cam, it sounds interesting.
I believe the heads (either original or Vortec have 64-65cc combustion chambers combined with the 18cc dished pistons and some assumptions about deck height, head gasket volume, etc. I calculate a static compression ratio of 9.3 but as you indicate the dynamic compression ratio will depend on the cam. I may be pushing the limit for regular gas but I will know more when I can confirm deck height, cam selection, etc.
