Latter option is to buy a 48v bbs02 whose motor is correctly wound for proper pedaling cadence on 48v.
52v is not much of a stretch for the 48v drive and the firmware will not tell you to go
yourself
Other option is to buy someone else's mechanically busted 48v bbs02b and frankenstein the stator and controller into your current working drive.
You will get your hands dirty and learn a lot about the internals in the process.
Maybe not the best option unless you are mechanically inclined tho.