Update, so I borrowed a friends 825 race demon and currently have it tuned with 95 main jets, 45 power valve, 99 secondary jets (started with 72p and 91s, then 80,90 and 95 primary with 99 secondary)with 45 squirters primary and secondary. Each increase in primary jet size helped the car pull harder) Car has an off idle hesitation under load(need bigger squirter?) but pulls really well until you open up the secondaries then I get the same condition of popping out exhaust/cutting out and surging. If you keep the secondaries open it surges and tries to smooth out but does not. The car definitely runs better, sounds better and pulls harder then with the 750. Also spark plugs look good and are not real dark. Do you think a bigger carb might be needed? I also have experimented with the timing and currently have the 25 degree mechanical secondary in with about 14 degrees initial using vacuum advance, also used 16 degrees initial with 28 degree mechanical bushing. Timing changes has not affected the high rpm problem. I have also gone back through and re-adjusted the valves. The car will rev (no load in park) using primary and secondaries with no hesitation, bog or stammer.