So I still advise to ditch that slow-performance 3+1 trans.
the D100 is about 3600 pounds right. Make that 3500 with an A833, Make that 3400 with aluminum heads and intake.
At 3400 with a 390@ 185psi..... you are gonna have a lotta,LOTTA, fun, no matter what the rear gear is. Plan on installing a traction-aider real soon. And then you will have to figure out what to do about the violent wheel-hop, because if those chebby-type springs back there, and no pinion snubber,and no weight on the tires. ...... lol. Even a 318 does that; been there done that!
