My 70 dart thinks she's fat.

Ditch the big block and put in a nice 500 HORSEPOWER small block. Easier to work on, drives better, lighter.
No disrespect to small blocks by the way.
I know there's some bad *** la's & magnums. Ive just been MLK'ing (having a dream) about a big block dart since I was 15, I'm 42 now & wasted alot of years on the booze & hardshit that had me under a bridge for years but never gave up on my dream.