Funny you should mention that... Have you ever heard of 458SOCOM? It's basically 45-70 in AR friendly rounds. It's on my list of things to build. Works with any AR lower, just need the upper and it helps, but may not require, to have magazines for that. (Duramag makes them, but, they mostly just have a tweaked follower and a raduised outlet, which you can do yourself.)

I want a 308 for in close stuff dealing with steppers in level 4 plate. 308 still hurts enough to knock someone out of a fight, and if they are unfortunate enough to only be wearing level 3? Well, they are gonna have a really bad day. It's also better for large deer.

If you are concerned about your eyes, you will want to try a bunch of different stuff. Right now I have a SFO 1x prism that's delightful. No issues with my astigmatism, really easy to pick up reticle and I can bang steel very easily as far as I can see. (The farthest I can regularly shoot is only 100yds.)

There are lots of options available. Don't worry about that so much.