Interesting.
Of course if anyone needs 904 type gaskets, just let me know. I have abpout half dozen saved from the various filter changes. The filters always seem to come with gaskets - both a 727 and 904 gasket.
Today's is Carquest brand made by 'Pro-King'. Seemed a little narrower, but I have faith.
My issue with the junk in the threads was mostly that it would prevent propper torquing.
I used a thread file after cleaning the stripper and spraying down with brake clean.
Went over the pan with some 600 sand paper. hammered the high spots on a wood block, then finsihed with some 1600 paper.