SR20det ignition timing issues/engine getting hot

[doridoridori]

I have a Redtop SR (S13 SR20det)
it was refreshed a year ago (new rod/main bearings, new rings, stock bore,etc.) and before I ran it everyday no issues.
around the end of last year I had a metal headgasket installed/tomei cams, but that's it nothing else changed. I bled the coolant (upper/lower rad hoses get warm) so im sure my thermostat didn't just go bad sitting. For some reason the engine has been getting hot (200-210F). once it gets to 210F i just park it, let it cool down and eventually got back home.

Im assuming my ignition timing is a little off which might be the cause of it, I double/triple checked the CAS and it's spot on and when I go to put it in "timing mode" (let the car warm up 170F, pull the TPS connector, rev it 3 times around 3k rmps) the timing marks are bouncing quite a bit. I tried the sequence multiple times tonight and could never get it where it needed to be. Is there anything else im missing?? is getting it to set in that timing mode that inconsistent? im not sure what to do at this point but any help would be greatly appreciated!