Re: 1970 85 hp V4

[Don]

quote amuller:

OK, I think I do get it for the most part. Lots of yak-yak on the net about using a headlight switch, or even an ordinary SPDT toggle switch with a diode, to shift these motors. That would be easy enough to do, but has anybody figured out how to interlock the shifting with the throttle? Accidental shifting into reverse at high speed would likely not be good for the machinery or the residents of the boat. There should be some way to interlock the shifting with the existing functionality of a common mechanical shift control box, but offhand I don’t see how.

Sorry, but I would definitely avoid using some home made control box set up…Too much at stake here. First, the possibility for hurting yourself or others. Then, the strong possibility for damaging that gearcase.
Keep your eyes open, you will find a decent control box. Just be sure to get the control box with the big black plug. The yellow or red plugs will not work on your engine. I would test the shift switch with an ohm meter before paying too much for a used box that is almost worthless without a functioning shift switch.