My 261 has a 3-hole mount setup, but it's upside down to the other engine that got pictured. If I were in your situation, I'd probably fabricate mounting plates to bolt to the sides of the engine from 1/4" plate, or something similar, and use a donut-type rubber mount to brackets attached to the frame rails. With some flat plate, square tubing, and a little cutting and welding, nothing much is impossible. That's how we build our round track race cars. Under the sheet metal, virtually nothing is original!
Jerry
