That is almost identical to the concept we used to drive our arm with 2 F-P gearboxes last year. See the linked images:
http://www.joemenassa.com/Images/ROB.../IMG_5997.html
http://www.joemenassa.com/Images/ROB.../IMG_5812.html
This worked fairly well, although our arm application was low rpm, and a drive application would likely be higher. The idler pulley is key to getting enough chain wrap so that you don't skip teeth under high load. When designing your idler, be sure to make it adjustable so it acts as a tensioner as well.
Good luck with your design, and have fun!
Rob