That's pretty cool. For maintenance procedures like setting idle speed, the Factory Service Manual recommends connecting an accurate diagnostic tachometer, its like that for most bikes. As long as your tach works like a stock tach should I'd call it a win.
Thanks for posting your wiring, could you link us to the place you bought yours?
92 CB250 Nighthawk - partsbike
93 CB250 Nighthawk - partsbike
92 CB250 Nighthawk - project
78 CB400T - partsbike
81 CM400C - Project, on the road
73 CB750K3 - Long term project