The drawings seems to show that the motor mounts are set in place on the frame rails balanced left to right of the center line. Cylinder head position, shows the drivers side more forward than the passenger side. That of course is the way it has to be, to allow for the room required for the left side and right side piston rods mounted along side each other on the crank throw. That could mean that the exhaust outlets are staggered that way also (maybe 3/4").
I suppose if you had a large T square handy, you could centerline it (down the intake manifold), and measure outboard to a matching location at the fenders, it would give you a pretty good idea of the engines position left to right. Might be an illusion (at the headers) or the staggered set position of the cylinder heads.
