Re: Retrofitting a Tach? & Prop question?
RE: the tiny tach: take a look at the cabelas website. They sell the tiny tach for $39 USD. Just for grins, I checked international shipping, and they will ship air for 45% of total price or minimum of $40 (from their website):
All other countries
* Surface shipping and handling is 25% of the total order amount or a minimum of $20.00.
Air delivery is 45% of the total order amount or a minimum of $40.00.
I've always had excellent service from Cabelas, and quick shipping, no questions return policy.
RE: the prop: I have no experience with your particular engine, but my small Mercury kicker (Merc 110, 9.8 hp) has two props commonly available, one designed for use as primary engine on small boat (light load, fast speed), one designed for use as trolling motor/ auxillary motor on large boat (heavy load, slow speed). You might find that commonly available props get you close enough for what you're trying to do. This website has some props, and you might as well check Cabelas while you're there.