They all run oppy's and I run a single. I can run whatever I want to the engine. My problem is cost, I can get parts all day for a Briggs. Kohler on the other hand I've gotta work to find the parts, and then they will cost me a hand and leg. Then I'll have to take out the balancer and get someone to make a new billet balancer shaft, then weld the gear that runs the fuel pump on the end. That'd cost me money there, because I can turn the engine much over 5000 if any without that balancer shaft snapping.
All in all, think It'd be less of a headace to go with the briggs, but I really dunno haha.