Greg,
I have a 1960 Factory Service manual and it has the 60 hp wiring diagram with tach and relay box, and the 40 hp wiring diagram with tach but without the relay box.
Two problems. First,I recently networked my printer to the house and shop computers and the scan function has been in-op ever since. If you can send or phone me your address I can copy the 40 hp and send it to you.
The second is that there appears to be a mistake on the tach wiring for the 40 hp. I went over both the 60 and 40 diagrams to see what was different and I noticed the blue ground wire circuit is not complete.
I worked as a factory service engineer for forty years, using wiring diagrams daily, and it is not uncommon to see these types of mistakes.
The two models are wired basically the same, except in the 60 all the tach wires go into the relay box and two of them, black (power) and blue (ground)terminate at ground and power terminals at the regulator. The 40 tach wiring all goes to the power head and the black goes to the terminal strip. The blue also goes to the terminal strip, but it also grounds the key switch panel. So there is a blue wire from the tach, there is one from the switch panel, and there is one from the terminal strip, but there is no junction shown tying the three blue wires together.
If no one can get one to you electronically let me know and I'll send you one.
Don
952-440-six six