rear disc conversion from drums setup?

[TalonMotorFabrication]

You don't need to add any thing to your uprights you already have all the parts.
Take one work mate/vice, angle grinder with cutting disk and goggles.
Cut both RU8's off the uprights and clean off welds and uprights.
Tac RU8's the correct way round using the bearing carrier with the caliper in place to check clearance.
Use an 8mm drill as a center dot, TAP IT don't smack it!
Mark each part and cut through tacs.
Drill both RU7's with pilot holes then 11-12mm clearance holes depending how close the other holes are.
Weld back together and paint for that I was never here finish.
Cost's nothing...