Those are ASD6 Drop Box Drives. There is not need for wedge plates nor counter rotating engines as the drives have the rotation built into them.
That boat is a 32' Hustler that ran in some race class back in it's day with 330 hp Mercruiser's and it ran in the low 90's back then. Fiore set the boat up for racing and the drives were originally set up closer and the engines were really close as they used a cast manifold. Had to move the engines outboard more when they could no longer get those manifolds. Moved the drives also.
As for a Velocity, I would use the newer #7M drives for obvious reasons and the boat would run very well. One can build the conversion kits with these drives though.
The ASD6's were rated at 650 hp.
That boat is located in MD.