On the big frame strip down, not too difficult because most parts are finger tight .. well they were 30-40 years ago.
The SA spindle rotates a few mm but won't come out, I take it the bushings have siezed.
Some gentle tapping with reversed nut, block and big hammer have only resulted in a split knuckle
it is not a case of leaving if not needed , tightened there is masses of play.
I've searched, read the threads and it appears that the destructive route may be the only option.
Heat straight from the go?
Or drill the top of the cross pipe. liberally dose with a penetrative.. try again next week ?