low hp and torque

Sounds about right for chassis dyno. Did they work on the tune up while you had it on there or did you just make a pull and leave? It's not uncommon to find 30-40 hp with a good tune.
My 360 put down 320 and it runs 11.60s, How fast do you want to go? If you have the chassis working right that should be a high 10 second car.