First Welcome to the board.
I don't think you are going to find many that have experience with the integral head, though I believe we have one or two. Hydraulic lifters were standard for 250s that doesn't mean your push rods are going to swap. I'd get a set of push rods with the head.
If you do have an integral, then you have an HEI distributor. The HEI was detuned(?) for smog and I would suspect the cam as well.
You will find that Leo's is a good start, but it won't answer all your questions. If you really want bottom end torque, I'd get a 292. The problem with replacing the 250 with a 292 would be an additional 2 inches in block height and the passenger side motor mount would have to moved forward.
Larry
