if you can take a pic of calipers on your hub, I"d be willing to machine a few thousandths off for free.
but going to a 6 bolt or however it's bolted to the hub directly is a best way. you'll have a better rim too and even if you do get the hub adapter to sit still, the bearings in a stock wheel get ate up after a few months.
we're all hoping you fight thru this!
I usually only disc front, caliper/v brake back, but I seen this rim and ordered a 2 in one disc brake & sprocket that bolts on the wheelmy next bike I'm gonna either fight to do a disc and sprocket or just do a shift kit but idk.
back wheel setup is always the hardest part of a build