All good advice above. Certainly check the blow-by. Another way to check the compression is to turn the crankshaft over by hand. If you feel each piston compress and hold pressure like a spring (5+ sec), that is a sign of a fine engine. You should feel 3 pulses per revolution. You can pull on the alternator belt to turn it. If so, I wouldn't even pull the head unless you know you have a leak or really want to mill the head for better compression. Has someone suggested your head gasket is bad, and if so, why?
Changing to HEI ignition would be my next choice. I think you have electronic ignition in 1974, so fairly easy.