I have often thought about using a tractor or even a mower engine in a Model T frame. I think the power match of 28
hp or less would be fine. I think for your mazda truck you really need about 90
hp. I had a VW bus with about 40
hp back in the 55 mph days and it did ok but I blew one engine going 70 mph for a couple hundred miles. I think I used 3 engines in that old bus while I had it. I had to constantaly adjust the valves. Any way you are very talented (way more than me) and I look forward to seeing more of your projects...