Still an issue,
the Aluminess spacer I obtained was for 8x170mm.
In addition, I don't have any shop tools so pressing out the studs from my existing swing arme does not seem possible (I really don't want to tear up my swing arm either, monkeying around with the vice).
The main thing I learned from Dave @Aluminess is that they are engineered to compress the tire against at least two points on the arm/hinges. If you don't have this- just hang the tire out in space, you'll get broken welds from the bouncing.
So.... still dont' know what I'm going to do about hanging my 305s out there.