Join Date: Jun 2010
Location: Chilliwack, British Columbia, Canada
Model: 1984 Interstate "Canadian"
The actual disc on an Interstate is a nominal 5mm and a different off set than the Aspencade so your 9-10mm replacements are correct.
As far as turning the old ones goes like Ben said it probably won't last and would probably end up under minimum spec. Add to that the fact that the disc surface to webbing will have thick and thin areas and will warp easily.
Advise given here is free and comes with no warranty "Caveat emptor"