I think there has to be another cause of brake squeal (like pad quality or rotor issues, or non-retracting piston, or something) as I (and it seems others) have managed to get squeak-free brakes on ouir CB750s (or whatever). In May 2006, I had the infamous brake squeal (wasnt so bad) and so dissassembled the front brake, cleaned up the piston side, new o-ring, cleaned behind the stationary pad, applied some Dow Corning Silicon grease to behind both pads and squeak was gone - lasted all season (May -Dec; couple of thousand miles).
So my point is, the SOHC bikes didnt come from the factory with squeaky brakes so its NOT really the nature of the beast...
good uck,
Andy