Would solid tappet produce more consistent valve opening at the upper end of that 6200ish rpm range? I had valve float on that SBC once after missing 3rd gear. Exhaust valve hit piston and bent valve. Luckily had TRW forged flat tops in it. It only put a faint scratch on the piston. That was only a few weeks after my dad and I had put it together. Cut in new valve, junked the old HURST shifter and put in a Mr. Gasket Pro shifter with extra small pattern. Not saying anything bad about the HURST, it just had too long of a pattern and handle. My knuckles hit the radio knob is how I missed 3rd gear that night. It was the shifter that was on the Muncie when I bought it.