Wow! It sounds like he recovered from his strokes very well and you took such good care of him. Some older dogs will develop incontinence even if they were never paralyzed. You are lucky he is a boy. You can get him male doggie diapers called malewraps. They are a wide belt that goes around his waist and fastens with velcro. Inside you put something absorbent, like a Poise pad or whatever will catch the urine. Change him as needed.
You will probably need some ointment to protect his skin if he is wearing his diaper all the time. My dog wore a malewrap 24/7 for 2 years. We used diaper cream to prevent him getting redness. White diaper cream like Desitin contains zinc oxide, so you can only use it if he does not lick it, because zinc can be toxic for dogs if they lick enough of it. My dog did not lick it, so it worked really well for him. I like it because you do not have to put it on every time. It usually lasts all day or longer.
You will want to keep an eye on his urine to be sure he does not develop a bladder infection. There is no problem as long as he is emptying completely when he pees. However if he is not emptying completely, the urine that remains in the bladder too long can create an environment where germs can grow, and that causes an infection. If you think he is not emptying completely, you can help him by squeezing his tummy to get him to urinate. We have a lot of information on that here, just ask if you need it.
The issue of bowel incontinence is something you kind of just deal with the best you can. The key to managing it is to feed him a diet that produces good stools. You do not want soft smelly stools that stain the carpet and smell up the house. I've had really good luck with Science Diet w/d dry kibble. It creates dry, well formed stools with very little odor, and they do not stain the carpet. I found that even if my dog doodled in bed and a stool rolled under his hip, it did not get gummed up in his fur. Other people have found other good quality foods that create good stools for their dog. If your dog has soft stools, you may want to experiment with his diet to firm them up a little. You don't want him constipated, but you can't spend your life scrubbing spots on the carpet, and it's better for him, too, if there is less smell and mess.
Some people stimulate their dog to empty the bowel. This is called expressing the bowel. It allows you to get him to empty at a time and place of your choosing, so you find less surprises. In my experience is it not 100%, he may go more later, but it does help. Anything you can get him to empty now, will not come out later. Here is an article that describes some good ways to stimulate him to empty. The ice cube method is good. I like the pinch method best. At the end is a list of videos showing demonstrations. The only thing I would say is, this works great with a paralyzed dog. If he still has some feeling and doesn't want you messing with his bottom, you probably just have to respect his wishes and buy lots of Kleenex to pick up after him. viewtopic.php?f=5&t=18586
You said the paralysis is starting to come back. I assume he is also having some trouble walking? This is so common with older dogs. You may see a progression where he needs more and more help. For example, some dogs can still walk but they need help getting up, then they are fine for a few minutes at least. Later they need assistance with a sling or harness to help them walk. I can't quite tell his size, is he about 25-30 lbs? If he is heavy, you might want to buy or make him a wheelchair to take the burden off of you. If he is not too heavy, then it might be enough to just help him with a sling as needed.
Since he will be lying down more, you'll probably need to help him up and get him moving several times a day, because it's good for his skin and joints, and he'll love it! It is SO important to be sure he does not wet his bed and lie in a wet spot, that can cause a bad skin problem very quickly. This is another reason malewraps are your friend.