I just got started with my LS swap. It appears to be pretty complicated since there are about 5 miles of wires laying in a pile on my garage floor.
Another thing to consider the fuel system. The LS requires from 44-58 psi of fuel ( I think the LT's require a bit less, but more than the stock engine). This has led me to consider using the LS long block with a conventional intake manifold and carb to get it into the frame and operational. Then I can upgrade the fuel system after I collect all the expensive bits.