Still one more problem with original 340

Ok, I got the fuel problem fixed on dad's challenger, Since its getting the proper amount of fuel now, the car will cruise without surging. I appreciate all your help. The only problem left with the car is what I believe to be a lifter/cam problem. When you accelerate easy now, the car does fine, but when you get on it, the car stumbles and backfires. Also, it has a bad tick at all rpm's, and does not go away when it gets warm. Soooooo, I pulled both valve covers off and disconnected the coil wire, and had dad crank the engine. What I found is that on the #8 cylinder, both rockers barely move compared to the other three cylinders on that head. Also, on the #7 cylinder, the intake rocker barely moves about half the stroke of the other rockers on that head. Now, I pulled the rockers off and pulled the pushrods, they are not bent or anything, and the shafts are installed the proper way, so they are getting oil. I think either the lifters are bad, and are collapsed, or the cam is wiped. The engine is all original, and I can't see why the original cam that has 31,000 miles on it would suddenly wipe three lobes, but it is very possible. I won't be able to pull the intake for a week or so, but I wanted to get some opinions until then. Could a collapsed lifter have that much slack to provide the ticking and the slop to not allow the rocker to move that much, or could that only mean cam? A compression test wouldn't tell me anything I don't already know would it? Anyways, I think this is definately causing the car to spit and sputter at full throttle, and causing my tick, now its just time to fix it. What do you guys think?
By the way, car is a 1971 dodge challenger r/t 340

Thanks,

Will