What about some things like,
Glucosamine for healing his joints,
One big thing that I think athleates use is Glutamine, I think this is really important if you are over training.
Another one may be the old humble Vit C, that helps reduce muscle soreness.
Everywhere I have read is that Tribulis is rubbish. If you want a product that actually has studies behind it that prove it boosts Test levels then ZMA is the no frills one, You would want to buy it from America like I do other wise you will be ripped off in Australia http://www.bulknutrition.com/?products_id=1041 Try comparing that price to Australian sellers even with postage 😆 This might not be what he neads though?
I undestand what you mean by no fuss, maybe best thing to d would be get your dad to add 5-10 grams of Glutamine to his post workout drink. Does he take a post workout drink, this could help with his recovery. And take 2000mg of Vit C a day.
Another thing might be making sure he does not over train Kinmassive, when you get older you need a bit more rest.
Let us know how it goes.