Son wants a thumper cam...which one?

It's hard to recommend a MP cam after all the problems I've heard about, but something similar to a .484 Mopar cam would be nice.

Maybe the Comp Cams PP284H. It should work with the 3.55 gears, especially in a smaller car. They claim a "lopey" idle, but still strong midrange. They sell lifters separately, don't forget to order them too. Always a good idea to use matching springs.

If the budget permits, a hydralic roller cam would be nice and give you peace of mind. Look at the XR274HR-10