Rear Disc Issues - 8 3/4” Rear Disc Conversion Kit

Appreciate the great advice everyone, I might have to think about it some more as I'm keen to try and get it right.
Best options that I currently like are countersunk screw through SBP holes, dorman studs or find some correctly sized discs that fit the axle register properly-still not so sure about just using as is though. Thanks again.