Brother "if" this were for me and I say if simply because its a big decision but IMO a necessary one, I would move into full hrt. At 62 hormone is not in proper function as to the axis . So you have to understand at his age, he went from one extreme to the other. When you go from a test level he had into test of that degree, 500 mg's, its this mega high and you feel as though you have strength. That's superhuman. So there is possibly part of the proble. Sometimes we want something back so bad that we may convince ourselves it is back and we push harder than we should.
This is one reason dbol bugs me for even the younger guys, you are able to use more of your strength than intended and more injuries come from these type compounds than just general gear. Think about the stories of people doing superhuman things such as lift the front of a car off of someone when the jack failed. That's adrenaline in large quantity allowing you to use all your strength as opposed to the amount of strength we are intended to use. Dbol is sort of doing the same thing so you are much more injury prone.
So this is sort of what happens often in an older person when introduced to gear. No, its not dbol but it is closer to the equivalent for someone his age when compared to the 25 yr old running dbol. He is using more muscle as it kicks then he is really supposed to and did not have the necessary time to solidify muscle that was not in its peak for a long time. So maybe one says "well he's been working out his whole life though". That does not matter when you figure what testosterone does. Test allows you to use the protein put in your body and after all of the complicated conversions improve muscle and muscle mass. Explains why the 25 yr old is much less prone to injury and has much healthier muscle. As you age and have far less test in your body the protein, even in high volume, can't do its job fully and muscle gets weaker and weaker over time.
So here's what I do and this is my opinion only so talk around about it and if you feel comfortable in his doc talk to him and or consult a trt doc or an endo as well. I personally back the test off now to about 150 a week. I would also if in his shoes begin hgh therapy at 2 iu's a day depending on strengh of product. If he could get Eli for example from trt doc then I may go 1.5. Whatever the case this is full hrt over trt. Now he is supplying both needs of the axis and IMO much better ability to heal. The trt IMO would begin today.
Ok so now let's say weeks have passed, dad ordered his hgh and he is and has been on hrt for some time now. Doc at some point gives him the green light to get back into the gym nice and slow. From here I do what he should have possibly done to begin with. Stay on hrt, no cycles for some time here. He works out but its never any max stuff, ever. He works wih medium weight being relative and just works and solidifies those muscles. Nice and slow because there is no reason to end up back here. His bench max and show off days are over! Lol..just nice and slow and steady and be the turtle here. He can get himself very healthy and looking like that 70 yr old doc that's all over the net over a couple yrs. No reason to push to hard here, the slow progress is progress and that's what he wants, turn that clock back for a while and let father time fall behind in the chase.
So now you begin to talk cycle levels maybe a year and a half or 2 yrs down the road. Maybe drove the hrt just a tad higher and by using our bloods as a roadmap Dad is sitting around 800 for a good half yr and by about the 2 yr mark his muscles have taken on a little size, they are harder etc and he feels he can do a cycle now. That's great but remember, these are not 25 yr old muscles so work smart in the gym, don't let the hot little 30 yr old with a daddy complex that's been eyeballin you get you out of focus. . She wants him without the extra plate on the bar so think, don't react to the inner caveman that wants to showoff.
I know much of this is not what you came here about but I'm thinking for now and later so this does not become a pattern because I've seen those patterns and they make people give up. Any questions let me know and again, I might run this by your endo so the bloods can be followed but right now the heal is most important trying not to slip back farther then later we rebuild the body nice and SLOW. To me its satisfy both needs of the axis though and you improve the chances of some clock reversal. Hope it all works out for him, I hate that he is so pumped up about this and has this much of a setback so just help keep his mind in the right place through motivation which I know you'll do.