The two inner bolts are hex head.
From the factory they were 7/16 carriage bolts. They engage the square holes in the bottom of the engine plate below the crank pulley.
breezy is going to eventually get to the head on that bolt. Maybe raising the engine will give him enough room to reach underneath and maybe put some downward pressure on the head so it doesn't spin. It's definitely a tight spot.
When I restored my front engine mount, I needed to weld and reshape one of the holes. A previous owner had used a hex head bolt with the head ground off at an angle so it would fit through the hole without hitting the crank pulley.
[on edit] breezy, maybe grind a slot in the end of the bolt with a cutoff wheel so you can hold it with a screwdriver.
