The Al Show is right some used to use the same type of chain
used in early GM front wheel drive cars ie: Toranado for the paralell configuration. Early twin engine fuel cars used a "greek coupler" double row chain with a sprocket on the front of the rear
motor and the back of the front motor. Pretty strong actually, but plagued with problems. No flywheel was required on the front motor (hard to balance) timming was a pain, lots of choices. Fire both engines every 45 degrees or 22.5? Weeg had the best idea
talk to the tractor people they have it figured out