Options?
A friend with an 8" chuck...
Flycut that sucker on your mill...
Tapered arbor held in chuck with a tailstock center, if you can drill any kind of central hole init, a typical flywheel cutting setup...
Mount it to your faceplate...more holes needed, maybe even blind tapped ones...not with doublesticky tape though...don't try that.
Do let us know how YOU solved it please...
HTH,
PaulS