I have no clue, myself. But, your situation gave me a thought. I am wondering if we might could come up with a thread, in "Project Shop" folks could supply info, about parts from other model Hondas or whatever, that could be used on others, with little or no modification? If we could develop such a thread within here and make it a "Sticky", it would be there, at the top, to provide info for those wanting to make changes of components, for whatever reason. Of course it would take awhile to get much info on there, but if it was already in place, this "Speedo & Tach" question, might have been answered in there and this member would not have to wait to see if anyone had already done this swap or another member might have posted info on finding the info.
Might work, might not. Just a thought, that might help out.