DnD 5e: Into the Borderlands/Caves of Chaos
I love B2, it was my first module as well, and have run it more times than I can count on one hand - including in 5e, though self converted. I also don't have the new conversion of B2, and wouldn't be buying it. I'd make some changes to the module (based on other's suggestions and experience) and a lot is up for interpretation. I don't know that this is the best idea either as doing it play by post isn't going to be able to match your nostalgia for it.
I'm not fond of 5e I much prefer the original Basic B2 was made for, or other TSR versions of D&D. I also prefer those rules because they're much simpler which works better with PBP. If you're not set on 5e, I'd be happy to run it in MM LL+MF+AEC (which is a clone of Basic/Expert D&D + Gama World type stuff) You'd still be able to play a Tortise mutant (though not exactly a cleric, but might be able to have some healing and/or other mutations), and a Moktar (cat person, though not a rogue - more like barbarian) or Cat mutant, though not exactly what you asked.
If you're really set on 5e, I'll consider it. I'm familiar with the core of 5e, but don't know much about the expansions, are those races/options available anywhere else? The house rules I'd make is that I prefer a bit grittier rests, but the gritty rests option seems a bit too out there, so I'd like to try a full 3 days for a long rest and 1 sleep period (4 or 8 hours sleep/meditation) for a short rest once per day (I'd rather go with something closer to previous versions of D&D like 1 hp per day of rest, but not sure what to do about fighter second wind and healing hit dice etc. anyone with ideas feel free to give em to me.) Same for Flanking, no flanking makes no sense, but the option for advantage is a bit much, so I'd go with a +2. I generally prefer not to use the multiclass or feat optional rules as they're prone to a bit too much wild variances of power between characters. I also like to give basic humans an extra +1 to an ability score of choice as they otherwise are under-powered.
The ability score array seems a bit on the high end, you're supposed to be able to grow into your character with the ability score increases and starting with an 18 which will probably be 20 after racial adjustments, which means you don't have anywhere to go. Seems a bit much. I do agree the standard array is a bit weak though, and would change the 15 to a 16 but I can live with your array, especially as everyone will be in the same boat, and it still won't save you from a horde of angry Kobolds. }:)-
I don't have any issues with your other requests other than what other players play, as that's up to them, but you already said that was negotiable.
As to posting, I can usually do a post or two weekdays but usually not on the weekends and holidays. What kind of posting do you prefer?