You could drop a 454 making 500ft lbs of torque in that thing, and while it might break the rear axle, it would still be a crap ton slower than if you put the right gears in it.
Edit: No need to look into it. The gear ratio sucks. Find/buy a 3.73 rear end, or have your gearing changed, and you will be FAR happier. Note that the 7.5" rear end is pretty crappy in the first place, but likely won't be an issue. You will also want a posi unit (may already, but won't work with 3.73's) or a true-trac. You will need the additional traction.
Maybe it's how you try to launch. Shift trans to manual low, hold down brake, stab accelerator to floor, when engine reaches 2500 to 3000 rpm release brakes. Have fun.
I think it is the torque converter it has a 2800 stall Ima put a stock converter in
Wrong stall speed torque converter or too high rear end gears (hiway gears, 2.75:1 ratio)
It seems to take off okay but when I hit the gas it revs and it gains speed but very slowly doesn't slip or anything also reverse is kinda chuggy when i back up what could be the problem
