Swap A833 for Auto - 71 Duster 340
What I do know is that it is a '72 340 bored 30 over with Edelbrock aluminum heads, Air Gap intake, Comp cam, and Demon 750 carb. 8 3/4 rear with 3:23 gears (wanting to go 3:91 or 4:10) Running 275/60 street radials and it will not by any stretch of the imagination smoke those tires with 3:23. Hell it won't even scratch them!
heck no; that is very noice!
I get an average of 156.5 and you are somewhere around 1000 ft elevation, so that's looking like about 9.9 Scr with the factory 268 cam in at 64* Ica. That's looking mighty good. With headers, a free-flowing exhaust and the rest of your combo, Ima guessing that should be hitting better than 320hp, if the tune is good.
So, you got a very good baseline there; we'll have to work on the tune to see where it's choking. I think the tune has been talked to death already, so you'll have to sift thru the thread to come up to speed.
The 3.23s are a good gear and the 275s are what I would run.
So, if the tune comes up good,and don't forget that cam-timing is part of the tune; altho with your pressure, I don't suspect a problem.
So then, I would be testing the trans to make sure it ain't slipping, and
then testing thechit out of the TC cuz Ima thinking unless you got a ton of cement in the trunk, she's either a very low stall, or the stator is hooped.
But before you do anything,
verify that your rearend really is a 3.23.
A 2.76 for instance will kill about 15% of your torque at zero mph, which could be more than 40 ftlbs at 2000rpm. If the TC is simultaneously hooped, that would make for a super lazy take-off