mph to low maybe wrong gears?

crackedback said
Post up a couple slip with all incrementals.

It's likely a tune up/fuel delivery/converter issue.

It's got to be laying over, stop pulling? If you have PV plugs in in it with that jetting, I bet it was surging in high gear. No PV's and a 4781 carb, I'd have at least 88 squared jetting in it! Don't know what you have for idle and in gear vacuum, but I'd put a 3.5-4.5 PV in the primary and see if it picks up... I think this is the major part of your issue.

Where does it stop pulling and what RPM are you going through the lights. Might have a bad converter in it. It's a good 10-15mph slow for the ET. I'd expect it to be running in the 117-118 range with that 11.30 ET

Go to a site like Wallace and look what the engine RPM should be for a tire size/gear ratio for those MPH and compare to what you saw. If the engine is revving way above the expected number, you may have some BIG slip in the converter.

Make sure all timing parameters are correct.

the carb i was running has 76-76 jets and pv plugs im gonna swap to another 850 i have maybe ill try your combo 88 squared 3.5-4.5 pv ,do you run that combo in a similar set up to mine, converter doesnt have much stall but doesnt seem to slip i had it rebuilt, its a good billet front unit with a anti ballooning plate and a good stater bearing i think its called.she runs like a bat out of hell for 900 ft then yes the surge and i played with the fuel pressure fom 5.5 - 8.5 psi, converter is 9.5 im sure a big dollar 8 inch would help maybe next year.