i did the swap in my obs truck 2 years ago.used ayou may of seen my truck up at the dunes.
First off let me say that LS swap is very worth your time, their reliable, fairly easy/cheap, and parts are super easy to find. the price of ls motors are dropping aswell you can get a 5.3 pull out for like <500 bucks now.
I used a 6.0 LQ4 out a hd in my swap form Grand valley auto parts. i had a wire harness built by baker engineering. from their its fairly easy. ls1truck.com really helps out alot. I did a cam long tubes intake and a built (4l60e)trans with 3600 converter. it was a pretty quick truck.
heres a link and some pics on gmfs (pre sas)
even with my big cam and matching converter i was still getting 12 mpg /14 highway on heavy ass 35s and 20s. it was a reliable ass truck even after running in down the drag strip at the dunes all day i always drove it home!
*link to a idle vid*