... can I safely assume if I buy the cam/lifter kit in any of the cams recommended that I can use stock length push rods?

I pulled the lifters and cam yesterday. WOW!!! 8 of the 16 lobes were ground way down and the lifters ranged from severely cupped to having the lobe worn way down into the lifter as if it never rotated at all. The other 8 oddly looked as if there was none to extremely little wear on them. All the lobes and lifter with crazy amounts of wear were in the middle of the cam with both ends looking new still.

What the heck would cause that!?!? The cam was in for 16 yrs with 10-20K miles on it since I don't drive it daily. I'm not sure when this happened with the cam. The last time I drove it had great power then made rattling/knocking noise lost power and died.