Rear disk for 8.75 with SBP?
I think the people that want to keep the small bolt pattern probably have rare or expensive small pattern wheels that they want to keep.
I think the kind of enthusiast that wants discs on the back also wants the big bolt conversion, for a much,much wider wheel selection.
I have some small pattern wheels i would like to keep, so a front disc conversion that still keeps the small pattern interests, but to do a rear.... i would go big pattern on both ends
But absolutely do one for your car! Love to see procedures and results.