Tap & Dies for chasing threads on M1873, M1892 rifles|Restoration, Repair and Maintenance|Forum|Winchester Collector

I am looking for taps and does to chase the threads on several older rifles.  I am well aware the screw threads used on older firearms are not today’s common thread series.  My current problem child is a an 1892 production M1873 that has screws that are a bit messed up.  I would like to chase them and have not been able to find suitable taps and dies.  

Thread forms are one of my many interests.  Considering that William Sellers did not propose the 60° thread form until 1864, and the Whitworth thread for with its 55° included angle was proposed in 1841.  I am not sure what Winchester used for a basic thread form.

I find the list of common screw and thread sizes listed in the For Collectors Only series of books interesting but I would like to find taps and dies to chase the threads.  

I am also looking for a 6-42 bottom tap for cleaning up the front magazine mounting screw thread on a Marlin M1889 rifle.  

Geoff