MH 30 Ground and 6 to 12 volt

I would recommend only 2 things that aren't mentioned if you go this route.

First don't tie all your terminals to the under dash (cover) components as shown in the diagram, use a terminal block made of 3/4 in plywood. The reason is that the space is small and your using heavy gauge wiring and your instruments are delicate. The terminal points are pretty close together some just 1/2in apart. Cut a piece 3in by 4in and a piece of innertube the same size. Put the tube under the block and drill a hole for a screw that will hold the block to the air breather tube plate. Countersink the head a little in the block. Next take the rubber off and turn the block upside down and drill 3 holes 1in apart. These are your terminal bolts. Countersink to bury heads past surface level. Put a generous dab of epoxy cement in each hole and put a bolt in each of the 3 holes. Put a nut on and screw down tight. Put the rubber on again and put a bolt in through the rubber and block and attach to the air bracket. The rubber prevents the heads of the last 3 terminal bolts from grounding to the frame by accident. Now you have 3 terminal connectors that you tie wires to. Put on locking washers on all connections and when your done, spray with electrical varnish to protect from moisture, or you can even devise a cover for it. Another advantage is that if ever you have to seperate the frame all you have to do is detach at the block instead of fiddling under the dash cover. Second is to use a 60 Amp Ammeter instead of
the original 30 Amp.

Your original starter will work fine on the 12V but should not be cranked for long periods.