Be that as it may Rob but theres no way a UNF nut will happily fit on a
7/16x 26 tpi thread on this side of the pond
email (option): deadsheds@yahoo.com
It's a 60 degree thread angle..not pitch...for these threads.
The pitch for Cycle thread is 26tpi with 20tpi as an alternative for some applications.(often the case with wheel spindles)
UNF at 7/16" diameter also has a pitch of 20tpi and the 20tpi forms will probably fit together..
If the thread tooth forms are identical it should be possible to determine the class of fit between the two by careful measurement...However, this would be quite involved, so the 'workability' of the actual fit would most easily be assessed by simply putting them together to estimate the suitability by 'feel'.
None of this is really necessary though as the correct Cycle thread taps and dies are both readily available for use in the remanufacture/clean up of parts..or the threads could be cut on a lathe...
I'm not familiar with the G3L so can't answer the original question unfortunately...Ian
email (option): ian@wright52.plus.com
7/16x 26 tpi thread on this side of the pond
BSC has 7/16-20 and 1/2-20 which are identical to the US National Fine.
email (option): britool51@hotmail.com
I often use 7/16" and 1/2" NF taps and dies to clean up 20TPI cycle threads.....It saves having two sets T&D's in those sizes.
I also often use a metric adjustable spanner to save buying an expensive BSF adjustable spanner 
Ron
email (option): ronpier@talk21.com
Hi Ron...I used the same trick myself...I just have the one Imperial lump hammer..
...Ian
email (option): ian@wright52.plus.com