This is something I did years ago whilst developing a five speed A65 gearbox. Just change the values in the boxes to suit what your using it for.
I found MPH in each gear for a set RPM made it easier to use.
I found a BSA wd type gearbox at the original George Yeomans Emporium at Drayton Mill in around 1977 marked MCR and upon inspection it did indeed have the Medium Close Ratio gear cluster. I bought the gearbox and the MCR ratios are now in my M.21.