Ross?
The frame looks like it, can't see the dropouts though. The fork crown is Ross, as is the chain wheel. Mid 60's? The serial number will begin with an "R" followed by the year in 2 digits.
I zoomed in, and it's a bolt-on setup, and you're right. There looks to be some user adaptation.Looks like a home made brake bracket. The chain looks like a one speed chain, maybe they used a 3 speed hub.
Enter your email address to join: