I did that swap last year to my 94 obs. you are only going to use a few wires from the obs harness to the 5.3 harness. Like power, ignition, fuel supply. Go to lt1swap.com and he has a step by step procedure including a chart of how to modify he LS harness and take out like 30 wires that u will not need. UR fuel pump should suffice. I had to uupgrade mine to 96-98 obs ccause the 94 doesn't throw enough pressure. I wired my stock obs gauges to the nbs harness and everything reads accurately.

Tips: U can use your original a/c compressor. Don't know what style u have but definitely doable. Can use the obs radiator. During the swap is a good time to upgrade to electric fans. One last thing, please do think it's a weekend swap and that's it. Plan to have thr truck out of commission for at least a month. It took me 7 months on and off to get the swap done. Then another 3 months on and off to fix some bugs.