im still not sure if you are referring to the swinsid x2 board or a stereoswinsid from schrab. Nonetheless I think that the easiest option would be to put a nanoswinsid in every sid socket and then remove the redundant components from the board.
Something along the lines of Schrabikus' design, sized to fit the MB6582 layout. I thought about ready made nanoswinsids, can't recall the EU shop that was/is selling them, but the cost is close to the cost of a real SID and I have the tool chain to burn my own Megas, so...
Exactly what error are you getting?
This has popped up with both 6.3 & 6.8
"Loading D:/Downloads/Docs/SWIN SID/Swin Sammich/base.sch ...
Error:
line 1, column 123: This is not an EAGLE file."
So don't know whats up but the PDFs are fine for me.