Thanks!
As far as I know/have heard:
Brian Curtis
built HL Yamahaframes for NortonVilliers, at the same time or right after that production he produced his own frames for Honda XL500 engines, the Curtis Honda, I've heard from 25 to around 40pcs. Inspired on the HL design, but with steel swing and plated. He also did 3pcs.? with Yamaha XT engine.
And this one, the only one, with Suzuki SP engine, based on the Honda, but scaled down to fit properly around the short Suki engine. This bike has had a easy life, the frame and swing is like new.