Just an update if anyone is interested, I successfully swapped the base plate last night. Wasn't all that hard and I can confirm a 53mm base plate will work as will a 53mm cover. Not that I ever doubted you Tim!
A few notes...you will have to solder. The ground is soldered to the base plate. There's wax. I typically do not use wax-potted pickups. It can hinder reassembly a bit. A heat gun, used sparingly and gently, will move the wax around. I also use clamps to ensure there's no gap between the keeper bar and the base plate when screwing it all back together as well as when I solder the cover back on.
I will say this...the burnt chrome screws with a raw nickel cover. A very cool look. I put the burnt chrome covers back on regardless.
Have them slotted in my PRS SC-58 until I get my build done. The bridge is a bit brighter than what I'm used to (I haven't touched the EQ yet) and the neck pickup is very sweet, really good, even though Eddie never met one he liked. Great set!