I plan to get the same kit for my re-bike, a recumbent. Fortunately, the whole seat support slides forward and back on the single rail of a frame, so I hope there will be enough clearance to keep the engine upright. Now, if I could just figure out where to mount the front support...
Edit: Perhaps I spoke too soon. I can't move it too far up or I will run out of legroom. Better do another photoshop mock-up. I'm a professional modelmaker, so I tend to overstress the modelling and planning part. Better to work out the details on paper first.