451 stroker rear gears question

Converter, as others have mentioned, is likely miles off. IMO, horrible selection for what you have. What size is it, an 8"?

New converters aren't and shouldn't be comparable to 80-90's units that slip like crazy on cruise. Plenty of new converters will flash to 3800-4000 and run tight when under light loads. Many run tighter on cruise than cheapy lower stall units. A 9.5" unit that is well built will get you in the right area.

IQ is on as well, the cam should be done around 5600ish, so the flash speed is a bit close to peak HP.

7000 with a 26" tire and 4.10 gears, I get ~20% slip... THAT'S FRICKEN HORRIBLE!!!