Recently purchased my 1992 NA 300zx with 89k original miles. Super clean condition so I wanted to make sure I was on top of maintenance. I finished doing the 120k just to be safe, timing belt, water pump, seals, crankshaft, thermostat, etc. OEM everything except a murray branded thermostat from oreily. Timing marks lined up and everything went relatively smoothly. First time turning the car over it developed what I figured was lifter tick. Did not sound like knock after watching numerous videos. So I shut it off without letting it warm up. Changed oil to 10w40, added some marvel mystery fluid and after starting the sound was gone and engine ran normally. I let it idle for about 15 minutes as I topped off the radiator with watter wetter, distilled water and some green antifreeze. Then the car slowly began to overheat, temp gauge crept almost to the top. So I decided to let the car cool down to operating temp and drove it around the block a couple times to try and get the fluids flowing. No noticeable loss of power but my oil pressure was definitely low, 15-20 at the 2k range and 30-35 when hitting 3k rpm and temp gauge steadily rose while test driving. So I parked it and I want to check my options before tearing the car apart again. Any help would be greatly appreciated.

First I'd confirm the T stat is opening. Engine at operating temp, is the lower and upper rad hoses the same temp?
I always place OEM or AM T stats in boiling water to test them before install.

Oil pressure sensors are always lazy as they get older, replace with new should fix.

Are both coolant temp sensors installed, plugged in, and operating properly? Test the resistance of the single contact temp sensor (info in FSM in my sig), this is the one that reads out on the dash, or simply replace it since they are cheap and easily accessible. See if there are nay codes, no CEL doesn't mean no codes.

Sounds kinda like the system wasn’t bled fully.