ORIGINAL: hobbsy
Shortening the rod would not shorten the engines stroke which I think is what you're driving at. A slight torque advantage can be gained by lengthening the rod and moving the wristpin higher and to the left in the piston but this is a lot of trouble for little gain, plus it increases the side thrust on the piston and increases wear.
Actually increasing the rod to crank ratio reduces the side load on the piston it also moves the point where the piston hits maxium speed as well which can be a good thing
it tends to let the piston dwell on tdc for longer alowing the engine to build pressure before the piston comes down