You may need the larger gear to bridge to the QC box.
From about 1892 Hendey made an early form of QC, the Hendey-Norton.
Norton held the 1892 patent for it. I don't have the number, off
hand. Your machine looks even earlier, though.

No, it specifically states Norton Patent gearbox, 1892, so it's at least
that new. :^) Besides, I thought the earlier ones were change gear?
The feedplate looks almost exactly like the one in the dropbox from a
couple of years back, except it says "Feeds 7 times threads per inch".
But as long as I have enough idlers to convey the power, the speeds should
work, yes? I'd make an extra gear bracket if I have to, though I suspect
there's enough adjustment in the current one so that'd not be needed,
though I would have to make some extra studs...

A couple of years ago there was a guy posting here from Torrington,
where they were based. He had some Hendey machinery for display
there, iirc. Perhaps you could scout out that city to see if anything
like that is still there. Frank Morrison

Good idea, thank you.

--Glenn Lyford