'63 bonnie I was building at the same time. Was riding with all harley guy's back then, the unfortunate design influence is pretty evident here. Ok on harleys but sort of an aberration on a brit.
Was a runner though, koni shocks, ceriani forks, alloy wheels, hi comp 800 top end, cams, ported, bigger valves, nitrous, water injection, belt drive primary, hydraulic clutch...
Eventually blew a rod out the bottom of the motor trying to get a 150mph run, that was messy. Was too broke to spring for the carello forged rods and 'paid the price'...
Still have it, mostly apart.
My back up bike at the time, '77 bonnie... currently looks pretty much the same but 'british racing' green, bigger brake and ceriani rr forks.