Those motors have a very high peak current. You might be better off using 24V motors, then the current would be halved and you would more easily find a suitable H-bridge to drive them, for example http://www.ebay.co.uk/itm/Double-BTS7960B-H-bridge-68A-Motor-Driver-Module-For-Smart-Car-Arduino-/121061024616?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item1c2fcca368&_uhb=1.