While not a bad idea to keep things on the low side, you don’t have to be ultra-concerned for a non-IR horse. There are lots of good options, but we need to know what brand you can get. One of the more widely available, low NSC, quality feeds is Triple Crown Senior, which is 11.7% NSC, one of the lowest NSC feeds, maybe the lowest NSC Sr feed
He stopped eating hay back in March or April;
I don’t understand this ^ in the context of all this below
He was definitely more satisfied when he had hay available and not hay cubes or pellets so I hope he is able to chew it.
What makes you think he wasn’t chewing it beforew? I understand some missing teeth (molars? how many?), but if he was maintaining better weight and was more satisfied, it seems he was getting quite a lot from the hay
Triple Crown Sr is a widely available feed, but there are other options that can be suggested if we know what you can get.
Waiting on cocosoya which is being shipped.
By always hungry, I mean he never seems satisfied. I’m feeding him about 20 lbs of timothy/alfalfa/beet pulp shreds plus the grass he gets grazing and it doesn’t seem like enough.
Not knowing still what “not satisfied” looks like, I don’t know how to answer that. It may simply be a mental issue that he was not getting enough chew time.
His vets have always told me alfalfa and beet pulp shreds so that is what I do.
Did they give a reason? Sadly, too many vets know too little about feeding 
His last vet told me to feed about 12 pounds of his senior feed a day but since there was concern he might be IR/ PPID I don’t do that. I think 12 lbs of grain is over the top for a pasture ornament anyway… a low starch pellet and first cutting hay would help. What do you think?
Pasture ornament, “just a trail horse”, “just a kids horse”, has no bearing on what a horse requires to be healthy.
What made you feel he might be IR?
Cutting of hay and quality is all subjective and depends on the details - type of hay, when exactly it was cut relative to its stage of maturity, how well the soil was fertilized, etc.
12lb of feed is not at all over the top for a pasture ornament, or any horse, if their hay/grass is not providing the calories and nutrition they need. You were feeding 20lb of concentrates already, just of a forage variety.
Your last vet had no idea how much senior feed he would need, so 12lb seems sort of random. I would assume, for now, that you should aim for transitioning to 10lb of the (let’s say) TC Sr, 2 5-lb meals, and see how that, along with bringing back the alfalfa, does after a month of being on that full time, full time.