Hi Ryan - Here’s a previous thread that might give you some answers: Pruning Old Apple Trees
My experience is, as others have mentioned, that going easy over many years (after you’ve removed all the dead wood) works the best. Slowly over many years I brought down a large wild tree to ladder height, going for wide instead of tall, leaving multi large main limbs. it looked somewhat similar to your good tree when I started. It worked but there’s no getting around that those large limbs stubs left in cutting large wood are not attractive. Cutting to the largest branch you can helps. It gets better as more new stuff grows (and it WILL grow! LOTS of pruning in the future). Since this particular tree is in our front (wild) yard I give more attention to aesthetics. This photo is after quite a few years of pruning. The large pruning is now done and it is looking better with more new growth.
Another multi trunked older tree in my fenced orchard I brought down from 25’ to 14’, again over many years (it’s hard to be patient but for me it worked best). One a year we cut off large low trunks leaving one, with multiple large limb stubs. It shut down production and amped up suckers (not surprising). Took maybe 4 yrs to get back to producing a small harvest. It’s a good apple and worth it but it has been quite a challenge pruning each year and I doiubt it will ever be an attractive tree again. Productive yes, but not attractive. If I were to do it over I would have left the many trunks and just worked to bring it down and out. But each tree is different.
Another tree was poorly before we started and big pruning didn’t help. It continued downhill and we cut it down. And it was in much better shape than your poor one. Seems best to cut that one down.
I’ve put some grafts on older large trees (mostly on watersprouts midway up) with varied results. Best when there is a decent space around the graft and it’s on the southern side.
I wish you the best with your trees and your plans! Sue