I think these reply’s are right on the mark. I am in the same boat on my 69 right now.
I chose to order a SPECTRA tank from a local vendor and installed it in my other car, a 68. It looks really good, better than the OER painted version. Fit well and appears to be ‘SAME’ as orig, but I really did not study all the curves, bends, folds, indents, welds and on and on,,,I was basically happy.
The option for a NOS replacement item is nice, at double the cost and dependant on condition and if you are a NOS or nothing kind of restorer.
I even called my local plater to ask about options for strip-&-plate ideas for an old tank,,,turns out to be a poor choice $ wise, safety & correctness.