Over heating following timing chain replacement

[WetSocks]

1997 ka24e 4x4 130k mi manual transmission

Summary of work:

Had start up rattle so I decided to do everything. Nissan chain, cam and crank sprockets, aftermarkets guides and a Martin Industries ratcheting tensioner. When reattaching the front cover, I bent over head gasket (yay.. didn't pull the oil pan, given the 4x4), ended up cutting the gasket flush with the block given it's not sealing out pressure or coolant at that location. No issues there, but I do have a very slight oil leak at the cover/oil pan meeting (SciFi, I used permadex ultra black, not the aviation #3, sorry)

I had replaced the thermostat with a Gates months ago when I did a flush and it was working fine. This time, I added a coolant leak sealant to the new coolant (had a coolant leak the first time I reinstalled everything and didn't want that to happen again!), wondering if that is affecting the thermostat. Also replaced the coolant sensor and sender with Beck/Arnley parts.

Just last night, I drove 30 min to a buddies to use his timing light. First problem was my temp gauge was not moving at all. Second problem, upon arriving, my engine was very hot, rad and upper rad hose very hot, lower hose only warm - probably just from the heat of the engine bay. I squeezed the lower hose and thought I heard bubbles (water pump?).

I did burp the system when filling with coolant, but not after I replaced the sensor and sender.

Using the timing light, I realized timing was way off, probably 20 deg BTDC. I couldn't get it to 10 BTDC, rotated CCW as far as it could go - probably at about 13 BTDC. Running much more smoothly, starting well, all-in-all, timing greatly improved. Before adjusting timing, I unplugged the TPS per the FSM, but did not set up the test with an OBDII scanner.

Drive back, still have the overheating issue.

I'm going to start with ordering a Nissan thermostat (not buying original was a mistake), but I am perplexed by the gauge not working. I can't imagine this would be because the thermostat failed, I would still be getting a hot reading. I have the original sensor and sender that I will put back in to see if that changes things.

Other new parts & fluids - NGK iridium IX plugs, NGK wires, using Mobil 1 high mileage full synthetic (no lifter tick), prestone green coolant. I have been losing coolant which I wasn't before all this. No leaks detected (haven't done a pressure test), and I'm not blowing white smoke.

Any thoughts?