Scored a newer logic board for my $50 2007 black MacBook2,1 - managed to get a 2009 5,2 board for $11 shipped after spending all day yesterday trying to get it to install Yosemite or El Cap. This new board should allow for macOS newer than those, and better performance. 🙂
Also have 8GB of compatible RAM to throw in it once that's done, and I also removed the SuperDrive yesterday as I bought it with a disc stuck inside and prefer the quieter operation of having no drive at all.
Good luck! It's not impossible to put a 5,2 A1181 motherboard in a black A1181 case -- the only thing to watch out for is that the screw bosses on the bottom case
won't fully match the screw positions on the motherboard (regardless of what A1181 variant you're putting the motherboard into), making fitting the heatsink problematic. One person used a copper shim to ensure proper contact between the heatsink and the CPU, but I find that kind of solution somewhat worrying (especially since they mentioned that in their case only one screw was able to fasten the heatsink to the motherboard).
IIRC, the legendary dosdude1 did this when he did his "World's Fastest A1181" CPU transplant mod, and solved the above problem by taking a Dremel to the plastic standoffs on the bottom case holding the metal screw bosses, cutting them from the bottom case, and simply supergluing them into the correct positions for the 5,2 motherboard's heatsink. I suspect that's what you'll have to do here.
Oh, and since you took out the SuperDrive, you'd might as well put in its place an optical drive bay caddy for a second hard drive or SSD (it's easy and affordable since the 5,2 used SATA for the optical drive, and SATA-SATA optical drive bay caddies are cheap and relatively easy to find). I've said before that this is one of my favorite upgrades for the 5,2.
Also: I had no idea the 5,2 could support 8 GB RAM. I've always seen 6 GB mentioned as the maximum, but after looking into it, I've just read posts from folks on the Apple Support Forums saying that they've gotten 2 x 4 GB DDR2-667 SO-DIMMs working. Wow. I hope you were able to get 2 x 4 GB DDR2-
800 SO-DIMMs for a good price! (I always complain about how expensive they are on here...)