Studying the photos in this post the lay out is the same mechanically as the Fastwin (19.5-22 CI motors) making a bracket will be required. If solenoid is not mounted under the cowl you may need to add wires. Unsure of how exactly the factory mercury switch works, I would presume it to interrupt the starter solenoid trigger from the ignition switch or starter button if this is the case wiring it in place of mercury switch would work. None of my engines had a mercury switch so I came up with this after a good scare which made stressful situation worse. Positioning can be challenging depending on size of switch. The ones with longer metal arms usually help I don’t like the ones with rollers on the end as they are typically too bulky. Honeywell V3L-1122-D8 is a good switch to work with. Though confirm specifications can handle amperage load of starter solenoid. I used this switch as I had a couple laying around. Currently I don’t have an engine readily available to photograph with modifications I have mentioned. Re sealing power head on my 1970 Johnson 25 hp, which had this modification installed.
