Sounds like a sticky thermostat to me. At least it's very easy ro swap in a new thermostat. As far as the fan, I was never happy with the gm clutch fan personally.
Technically you should fully flex out the suspension without shocks, measure the difference between full droop and full stuff, then measure shocks and order in the length needed. They should be the last thing to be done. That's what i do anyway. Usually a off the shelf lift like that doesn't...
Personally I don't think the thin stuff like lizard skin or asphault type abarrier helps much just because the thin stuff only blocks higher frequency noises which I don't think most cruisers emit much of. But I'm a amateur at sound blocking. As far as heat protection I used something similar to...
There should be a wire going to the brake switch I would think. The ecu needs to know if the brake pedal is pushed so it can know when to engage or disengage torque converter lockup. Although gen4 is different than my Gen 3, I would think the gen4 ecu would need this. Also keep in mind going up...
Actually I'm not able to weld aluminum. I made the cuts, cut a piece to weld in, then paid a welder down the street to weld it up. Was very little labor to pay him at that point. Just another option for you if you want if it helps.
I kind of like these shifters personally. Horseshoe Shifter for 6L80 swaps #1202 - https://www.kilduffmachine.com/store/p26/Horseshoe_Shifter_for_6L80_swaps_%231202.html
https://www.kilduffmachine.com/store/p24/6L80e_and_6L90e_Shifters._Cable_included_%231200.html
Maybe you mentioned it, but what do you want out of a LS combo? What is the main intended use of this cruiser? How much do you want to spend on the swap? You can use afaik a gen 3 motor with a gen 4 ecu. Which then you could use a gen 4 trans. You would need a dbw throttle body and a crank...
Saw this on craigslist. Might be an option. They have 4l70e transmissions listed which are supposed to be pretty strong, not sure if this helps but here is what I saw...
https://seks.craigslist.org/ptd/d/la-cygne-remanufactured-transmission/7236156010.html
What model Ls is that? Is it new or used? I believe Cadillac manifolds hug the block really well. Can't remember for sure...it's one of the car manifolds hugs the block really well and dumps slightly close to the center of the block.