This looks like the newer engine mount that fits when there's that little metal block welded in between the holes. It looks like the mount screws into the threaded hole in the center and no bolts on either side of the metal block?
John that is the correct looking mount with a bolt attaching up through a center whole in the mount threaded into that welded on square plate on the bottom of your front plate. I have the same setup on a '62 235 I have waiting in the wings. This design did away with the metal shields around the rubber mount, often leading to eventual deterioration of the rubber when the front seal leaks. These mounts are also known to compress (squat) over time along with the oil damage, sometimes leading to the balancer "rubbing" on the bulged out mount rubber.
Just my opinion, but I think Kevin's suggestion about a little further grinding in the head of the carriage bolt and opening the through holes in the front mount plate for the square shoulders of the carriage bolt to nestle into is a good idea.
