I have not rebuilt the ar5, but I have rebuilt multiple FWD, RWD and AWD transmissions and differentials. I have also rebuilt multiple engines, and in my opinion, transmission are far more complicated/difficult. I have not rebuilt an auto transmission, with the planetary gears and what not, so I have no experience there.
If there are some general tips I can help with, it is MEASURE EVERYTHING. If there is a specification given, meet it. Whether it be freeplay, preload, resistance, etc. If you don't have the proper measuring tools. Buy them, you'll use them again. At a bare minimum, you'll need a highly accurate caliper (some prefer digital, but maybe I'm old school in that I like mechanical), a dial gauge, a shop press, various sizes of 2 and 3 jaw pullers, and either braising tools, or a cheap welder. I have often had to weld together threaded sections of bolts to a mounting plate, that was adjustable, and rigid, so that I could mount a dial gauge to properly measure for free play, because those magnetic bases won't do ish on our cast aluminum cased ar5. I've also welded together unusually shaped press cups. I'm assuming you already have feeler gauges.
Put it this way, at one point, I rebuilt a FWD transmission. Four plus years later when I sold the car, the transmission was still perfect. A friend with the same year, make, model, trim level, etc, car, rebuilt his transmission. He had ever on going problems with it. To this day, if he forces it into R a little too aggressively, the transmission locks itself in a forward gear, and reverse. All he has to do is pull the reverse sensor plug, and tap it free, but what a headache when it happens. Put it this way, he wasn't as anal retentive about all the specifications. He's a very accomplished auto mechanical guy. He went to college for it for 2 years. And has done very good work. But this is the difference if you don't take measurements that you're supposed to.
As for beefing up the ar5, I think antonio (Sky888) is your best bet.
