I run 35's on 3" suspension and 1.25 BL. I have put around 140k on that size with a Tcase drop. I have never had a vibe or a problem with the slip falling out. But all jeeps are different and some are worse. I also have my stock MM's that are still going strong.
You can go to a salvage yard and get a XJ front drive shaft and have it sized for your TJ with a SYE. The u-joints give it strength and IMO tom woods shafts fail more commonly than others, At least in my area with trails and mud. But he does stand behind the DS so its not a problem of warranty.
You will be able to run 315's easy on the lift you have. The parts mentioned are great to have and are nothing but good for it, But not necessary. 315's are a 35" tire, Do you plan on stopping this jeep? How about steering? Thats where i would start. They are heavy and wear parts more and require more attention and maintenance/preventative. Mud ruts will snap you tooth pick tie-rods easy with 35's. Theres also alot more thats needs does at a minimum.
But you could get lucky, Theres always the guy on 38's with a stock set-up doing fine somewhere. Your on a good path for your rig but IMO you over looked important ones that control your jeep and if they break your jeep is down. Flex wise you can adjust up travel easy to avoid rubbing but at your lift height you shouldn't loose any performance. Good luck either way