Hi,

I have been out of state and now I’m wondering about the outcome of you getting the head back on the engine.
I doubt the tightness sequence would create enough gap to cause a space for leakage.
Chasing the treads out of any crusts of the block or head is always advised.

Sorry to hear about the exhaust bolt but since you will have the head off again it will be easier to access.
When it comes to removing a locked up bolt or spark plug “Patience” is required.
Most any penetrant helps but most importantly is how to strain the stud or spark plug back and forth or in and out is what works for me.
When you twist a length of thread you are stretching the material slightly and those stretch and rotation combinations are what helps the penetrant work. Vibrations will jiggle the crusts that developed within the clearances at the top and in the root spaces of each set of threads.
Heat and cooling is nearly the same thing but aluminum is fast in drawing off the heat and besides it evaporates the fluids. The PATIENCE is your best friend.

I also was wondering if the head gasket was the wrong one. The 2.1 liter engine may have gotten a B-23 gasket or by chance the rear freeze plug was removed?
The B-21 in the late seventies was the first cross flow design and it’s why it’s was call a B21 F engine.
Since cross flow was not such a big deal later on the engines dropped the F.

B-23 and B-230 moved in along with the turbos and LH change up away from K-Jets by 1984.
With that, said study the gaskets carefully for elongated gasket holes or bigger ones for more coolant flows in places.
I only have ever changed two head gaskets in my lifetime.
Once on my B-21F for an oil sweating right above the oil filter.
In the early eighties a Datsun’s 280Z. It had two or three different head gaskets.

So, I too was surprised as the engine rebuilder paid me to replace the wrong one after I had put my sister-in-laws engine back in the car and it leaked.
I took the engine to a rebuilder where a coworker of mine did, part time engine cylinder boring for $10 a hole.

Since it was during a recession of 1982 and I was laid off, it turn out to be a handy thing.
It was my first head job but they had confidence fir me since I pulled the engine in the first place, plus, it was a twenty mile trip for them to deal with it.
They bought the new oil and antifreeze as soon as they saw the gasket.

So wrong head gaskets can happen more than you think!

Hope to hear from you.

Phil