I have this kind of mount on a couple of my trainers. What I did was take plywood the thickness of my engine mounting lugs and made a spacer that encapsulates the mounting lugs and is held in place by the mounting strap bolts. All they do is prevent the engine from moving forward or turn from side to side. It's an extra step that is a pain in the but to cutout and fuel proof. A recent Avistar assembly the engine I was using fit exactly between the engine mount bearers, so I didn't even bother with making the spacers. Tighten those engine mount strap bolts securely with some loctite and you should be good.