From my research, and the bit of messing around I've done with mine, they don't seem to present any unique problems. They're an old-school Browning design manufactured with old-school manufacturing processes.
I noticed a quirk in disassembly (at least with mine) where the bolt doesn't easily release once the barrel is removed. I haven't yet determined if it's because of an issue with the barrel lock/bolt release (joint mechanism) or if it's a design feature to reduce the likelihood of slamming the bolt into the front of the receiver, but something to keep in mind.
The Model 8 doesn't have a firing pin rebound spring, so can potentially slamfire a round not stripped from the magazine. Model 81s do have a spring, so this isn't a concern.
Presumably you know they're all takedowns, and also know that they're long-recoil operated so that, when it comes time to disassemble, there's stuff under lots of tension
Numrich has a lot of the parts available, as does Jack First (at least according to my old book).