Help! Wiped cam lobes? - Video inside

Hello!
I would like to draw on the collective expertise of this great community. I have been trying to diagnose a carb backfire and Its really starting to stress me out.

It is pretty consistent and very noticeable under throttle. Sounds like a machine gun at higher RPMs. People have suggested that it is the cam shaft, but I would like to be a little more confident about that before I tear the whole engine apart. It is a 1973 plymouth duster with a 318. I have pulled the valve covers to observe the lifter movement, but I'm just not well versed enough to convince myself that it is a cam problem. A few of the lifters were a little loose and there was some play in a few of the push rods, but noting appears to be bent, and the springs seem to be fine. Some lifters do not move as much as others, but they all move. Also, some pushrods spin consistently, is that a problem?

I uploaded two videos of the lifters moving as I turned the engine over. Can anyone draw an opinion about the condition of the camshaft from these videos? Picture quality and angle sucks I know, but it was the best I could do.

Right bank
[ame="https://www.youtube.com/watch?v=HWz91fRITdM&feature=youtu.be"]wiped cam shaft? - YouTube[/ame]

Left Bank
[ame="https://www.youtube.com/watch?v=a8D88u8SZ4k&feature=youtu.be"]017 - YouTube[/ame]

Thank you for your time! I could really use a hand here.