Re: First motorized bike
Welcome to the forum from an old Miami native. You've got the right direction except for one thing. Do not rubber mount the engine. Resilient material will not eliminate the vibrations but simply transfer them to the engine mounts and fasteners. Mount the engine as solid to the frame as possible and live with what the engine produces. This is an old subject that has been hashed over here time and again.
Good luck and keep us posted on your progress.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"