Need a pep talk/help: can't eliminate exhaust leak after 5 attempts Options

[DC_neun_vierzehn]

Looking for some advice and encouragement because I'm ready to say "uncle."

I have a '73 2.0 w/ a fresh 2056 rebuild. Exhaust studs are new. I have new exhaust stud nuts from @rhodyguy . I have new Victor Reinz copper washers and exhaust gaskets. My heat exchangers (HEs) are stock (not stainless).

By using the shop vac blow up the tailpipe method, I have detected exhaust leaks on the passenger side (PS) at both exhaust ports as well as at the muffler gasket.

Here's the method I used on the driver's side (DS) and it worked perfectly: a dab of Elmer's glue on the copper washers to get them to sit in the heads and used the X pattern to tighten the nuts moving to the next nut after 3 rotations. Worked perfectly, no air leaks.

I tried the same method on the PS HE, but it failed to eliminate the air leaks at the head after 5 straight attempts of removing and reinstalling. SO FRUSTRATING.

Based off of past threads I found via the search, the only things left to try:

1. Gently file the HE pipes to square them off (use a Sharpie to mark the tops and only file until ink is gone using a large bastard file that will do both pipes simultaneously). I did not do this yet because the pipe ends look flat and clean. When I set one of the copper washers on the top of the pipes they sit flat and even - when I shine a flashlight behind that I don't see any light coming through.

2. Anneal the copper gaskets using a blowtorch - I have no idea how I would get the copper gaskets to sit in the heads after annealing them and then lay on my back underneath them while trying to install the HE sounds a burn victim waiting to happen. How does one do this safely?

I'll take any suggestions or encouragement because after spending 4-5 hours on this today, I'm feeling a bit hopeless.