my 2 cents....not 100% complete but....

As for motor mounts, street and performance. Vortec383 made a bunch
of sets a while back and might be willing to sell you a set. I have
also seen them for sale on Ebay, generic copies. I removed the V6
offset motor mounts and bought new V8 rubber mounts at NAPA and
receiver cup at a salvage yard allowing me to use the S&P type mounts
as designed. Street and Performance recommends you keep the factory
wiring harness in place, minus the connectors to the old engine. Buy
a stand-alone harness from a harness builder like S&P or isolate the
wiring yourself using a schematic. I had a post a long time ago
listing what wires I had remaining in my harness at the PCM and where
to hook up relay for fans and a fuel pump. It wasn't complete since I
didn't do the harness conversion. LS1Nica or Vortec383 might be able
to help you with yours. LS1Nica is in Afghanistan right now so he may
not be too much help. I didn't do a 4x4 conversion so I am not too
sure about transmission to transfer case compatibility. Considering
how many late model Vortec trucks, 4.8, 5.3, 6.0, there are out there
in salvage yards I would get a complete transmission and transfer case
from one of them or at least have a look at one and see if they are
different from what you have. I would think they would be stronger
units since they have to hold up to the increase power and torque of
the LSx engine. You will need a shifter for the transmission. A
Lokar unit looks cool, almost like you still have the 5 speed in
there. The transmission crossmember on my 92 2WD was just relocated
and worked perfect. I went from a V6 5spd combination, also. For the
fuel pump, I bought a 93 corvette LT1 model pump and mounted it in
place of the stock tank mounted unit. Many have used higher
performance models but the corvette pump worked great for me. If you
have the single inlet fuel rail, use it with a internally regulated
fuel filter from Wix. I think the pn is 33737 for the filter. It has
the high pressure side, return side for excess pressure and the single
line fitting feeding fuel pressure to the engine. Nice thing is you
get a new pressure regulator every time you replace the filter and
they aren't too costly.