On the chest piece I use Fortify Health and Stamina. 72 extra points in each is better IMO than regeneration of 0.67% of your total health and 1.4% of your total stamina per second in combat. You can get better stamina regeneration by consuming a few Vegetable Soups, or Venison Stews, and if you're on a PC you can use the CK to fix the bugged health regeneration for them to get better health regeneration as well. (I also almost always use light armor so I'm getting the benefit of the Wind Walker stamina regeneration perk anyway.)
Well, it depends on what you use your stamina for, how, and how often. For a standing power attack, you just need 1, and so a trickle of regen will be enough to do them occasionally, if not spam them constantly. Same with Bashing, which is effective if you block, bash, slash, and block again. By the time you've finished 1 iteration, you've recovered enough for another bash before your opponent recovers from the stun. That's also why I stacked so many instances of it (up to 4 in one build) so where 1.4% isn't significant, 5.6 is for the purposes of sustaining such a tactic. However, I completely abandoned this for the Drainheart Sword, which recovers it on strike in a dual wield (with a more effective primary weapon.)
OTOH, my main tactic is Critical Charge, which is stamina intensive, but requires a while to line up. During which, you can recover a lot of stamina with a little regeneration. Of course, that's often a lead up to Hack&Bash to take advantage of the stagger, only in a duel. (Can't be sustained reliably against multiple opponents, when the hit&run tactics would be more advisable.) A nice thing about enchanted Stamina Recovery is it keeps working even while expending Stamina, unlike Magicka Regeneration, so the constant effect really stacks up.
Stewing is another option, but it requires preperation, and runs out eventually like Achemy unless you're carrying around a bunch of pre-made stews. It can also run out mid-combat, assuming you don't count to 700 every time you dose yourself, or set up timers to warn you. If you depend on them to run you primary battle tactics, this can get you killed, or at least force you to stop in the middle of a fight, and re-up (Fortunately from the safety of the Inventory menu.)
And lastly, SR is availible in slightly different slots than HR, one of which he had maxed out in the OP. For the slots he had availible, SR might be a viable fit, depending on how he uses it. The choice is, of course, up to him...