9" Junior metric banjo

I have a 9" South Bend Junior/wide nine model C. According to How to Run a Lathe 35th edition dated 1935 there was an option for a banjo for the Model C that had a 127/50 tooth transposing gear to cut metric threads. There is also a chart in the book to show what gears are needed for what metric pitch using this compound 127/50 gear. I have a 127/50 compound gear. It is not original South Bend. It is 16DP which matches all the other change gears that are original to this machine. In the book it shows the banjo needed having the V type banjo that looks like the common banjo on newer 9" lathes. The junior banjo is 1.750 on the lead screw bearing vs 2.00 for the newer banjos. So in getting to my question does anyone have one of these banjos so they could tell me how long are the arms of the banjo? A 16DP 127 tooth gear is 8" in dia. Even if I bush a newer banjo I don't believe the arms will be long enough. I am perfectly aware of all gear compounds that will produce metric threads on an imperial machine. All searches on here show the 127/100 and others. None discuss 127/50. I am preparing this machine for sale in the future and since I have the gears I was going to include the gears and banjo for a metric thread option. If anyone has a 35th edition of HTRAL look on page 104 and you will see what SB published. Any help would be appreciated. Thanks.