I had engines bolted directly to frame, your set up maybe better for that. even with braces on mine they would still crack now and then. and they seemed to eat belts. They would stall now and then on a long run (overnight) When I got my RO I got a bigger diesel generator to run the shack, so having power on hand, I tried an electric motor and it worked very well.
so I changed 2nd bush for an electric motor also, run is with diesel welder (has 10000 watt generator). works well for me.