I have a 5.3 T56 combo in a 92 fullsize.
I did not use the shifter relocator that you mentioned, but it looks fine.
I bought a kit from Keisler Auto that moves the shifter to the front hole, but requires some transmission dissasembly and reassembly.
The only issue you might have with the kit you linked is it may hit the transmission tunnel. Mine is very close with the stock crossmember.
I ended up removing much of the original wiring from my truck, but not until it was running, and all the bugs were worked out.
It is a fun swap.
Good luck
'92 Fullsize, swb rc
5.3L/T56 conversion, comp XR275 HR cam .566/.568 lift 222/224 duration 112 lsa, crane dual springs, trick flow push rods, K&N Filter, Nelson Performance tune, Keisler shifter relocation kit, Boyd Coddington Smoothie II 18x8 235/55 up front, 18x10 295/45 out back, 2/4 drop, eaton lsd w/4.56 gears