Well, with series MCPCB I would look at chopping them up before replacing them, then you’ll know the optics fit. The job I did in my link above wasn’t pretty but that light pulls over 24 amps, that’s 8 amps per LED, so chopping and soldering works well enough. I didn’t even bother looking if there where replacement MCPCBs.
In terms of drivers, at least for parallel LEDs, Lexel might have something. EU based though: Lexels driver compilation
I don’t really know who in the US provides an assortment of drivers to choose from besides Mountain Electronics: Drivers