As did I back in 1984 with the 340 car, the .484 hyd. purple was ok but when I stepped it up from a street car to S/95% Strip it had to be an sft cam. the old DC. 590, which also ran great on the street on the few times I took it out.
I think the OP would do very well with doing the same thing and let that motor rev freely to 6k+ with a decent tight 4000 flash verter, then we would see how fast he could go as its capable of much more with the hp people say it has.