I'm not George but to answer your question, no. You cannot use the helical focusing ring from an early Bronica on an SQ or ETR series camera. There was a leaf shutter lens made for the early Bronica's but the rest of the lenses relied upon the focal plane shutter in the cameras. The SQ and ETR series cameras used leaf shutter lenses and did not have focal plane shutters.
Originally Posted by Geoffrey Ferguson
I read once where a fellow owned both an early Bronica and an SQ series camera because he liked the "look" of both lines of lenses.