All things considered, had a good day of progress, and a couple setbacks that would have bitten me.
I spent the morning reengineering my rolling engine pallet so that I don't have to borrow an overhead gantry to pick it up next time (thanks Bill). I can now get a regular engine lift under it to pick up when needed.
Next was the oil pan. I pulled the rest of the awd parts off the Buick pan and dropped the old one. Setback #1, the compressor bracket from the Buick attaches to the block and the oil pan. The LS1 pan, nor the conventional truck pan, have provisions for this. I think I'm going to need an ac bracket from an lm7 (Burgy's yukon xl looks like it should work, assuming the compressors are the same part).
Next, the truck motors have the dipstick tube in the pan, LS1 does not. The LM4 is probably the only block that is not drilled for the tube in the block. Most things I read said the hole was there and plugged, but not the case. A right angle drill and a couple custom drill bits and the hole was done. No big deal.
LS1 windage tray and pickup tube
Back on its pallet.
Setback #2. There's 1 broken exhaust manifold bolt on each side, and it looks like they're going to leak. So, I'll have to pull the manifolds and get out the broken bolts, and any more that break...