fattest cam in a 340?

I've got a '73 340 that is, to the best of my knowledge, stock internals except the cam. it's got an eddy 4 barrel, aluminum intake, and eddy valve covers, but the cam was not installed correctly, and you can't time the motor with a light. I also don't know the specs of the cam, so I've made the decision to swap in a new bump stick.

my question here is what is the highest lift camshaft I can safely run with a stock valve train? I want a mean LOPE, I want this thing to pound the concrete, I want to be able to jump a skateboard off these lobes.