I'm in agreement with others the bracket needs to come off the bike. it will also give you a chance to clean and paint it.
I agree and since he has the caliper off I hope he's planing on replacing the caliper seals, buy the kit from brakecrafters for 30 ish bucks and it comes with four new dust seals and plenty of brake grease. Also make sure you clean the caliper bolts with some fine sandpaper and lube them well.
My early(#442) 77' KZ 1000LTD has the same rear brake setup as your bike. The manual says it is different but I know it's original. It seems like the mounting bracket only goes in from one end of the caliper or it knocks the slider pin boots off. It took me a few tries to get it and I tore a boot in the process, order a couple extras.
Your caliper is correct for an LTD. The “A” models are different.