You're right AB! i was assuming those are small "L" brackets left attached to the horn. After seeing the close-up those look to be part of the casting, and i don't think they're large enough for 311 either. Amazing how daytime sobriety can change your perception.

Definitely large flares in the bass cabs, wondering if they are a custom job based on 210. Note that while "toed in" the front of the cabinet remains tight against the side wall. So, it's probably a safe assumption that they are not rectangular front to back.