I noticed this post is from 2012 but I was looking to do twin flat slide carbs on my race sled. I cut out a flat plate to match the engine side then created another flat plate to match the boot side and used 2” pipe to connect the two plates. Used a die grinder and hogged out the holes then attached them to the sled. If I had to do it again I’d use individual carbs instead of linked together ones and would have used different boots but it’s all I had on hand. For jetting I currently have 230 mains in them at the moment and am mixing my fuel 50:1. My ratios need some further tuning however for anyone attempting to do the same I hope this provides a starting point. I also have shaved heads on this engine at the moment and building 150 lbs of compression so my hope is I can run 108 octane. The other thing I’m not so sure about is the clearance with my secondary clutch. I might need to shift my adapters more to the right but for now it should work.