I have an 03 6.0l out of an Escalade. That means cast block and aluminum heads. I used the factory harness & sent it out to be paired down for what I didn't want and at the same time had the ECM reprogrammed.
The rest of my drivetrain is a T350, stock 231 (yeah, I know) 4.88's running 39.5's. The motor makes good power pretty much throughout & don't have much to complain about. I can't give any input compared to a 5.3l.
Oh, you mentioned oil pan. I had to change to the corvette oil pan because the truck pan hangs way down.