SYE question.. Driveshaft length?

I've got a '98 xj with rustys 3.5" aal's, tomken 1.25" shackles, and I've just installed 2" blocks. (bastard lift, i know) I haven't even driven it yet and I'm almost certain i'll have bad vibrations. I had none before.

So I'm thinking about getting an SYE with the tom woods driveshaft from rusty's. Since my setup is only temporary, will I be able to use the same driveshaft when I get a real 8" lift? Or will I need a longer one?

if you go to 8 you will need a different driveshaft

you should be able to throw a front driveshaft in there at your current height, but in not positive, someone else chime in

Sorry to drag it out more, and yes i've searched (web too), I've got a 98, 4" coils in front, 4.5" packs in back, np231, C8.25. Am looking at SYE/Shaft combos to install...but gotta question...What measurments for the shaft should I go by if in the future I add another 2-2.5"? what is too much? Also would I have to change axle shims for different angle if 2-2.5" higher?
Thanks in advance!!!!!!!!feel free to call me a newb