not doubting u retro. just saying that mine swapped straight forward on a number matching 76 f bike. chain was never out of alignment. now i have hte kz750 wheels and a DOHC tubular swingarm 2 inches longer than the stock f arm. lining the kz wheels up was a bit of a challenge what with finding bearings, reaming the brake carrier to accept the axle, finding spacers, etc. she also now has the 78 f3 motor in her which as u said does have the 10mm wider output shaft. coupled with the gl1000 front end, to me she rides like a dream and i can throw her around pretty decent.