Best carb ever is the Keihin CR round slide racing carb........No one in classic racing uses them because they don't think they comply.......Simply a round slide non pumper carb.........nothing super different there........But the way they work surpasses all the others........if in doubt, just look at all the classic in line Jap four race bikes, Honda twins/fours etc.........they prefer these over injection, so that says something.........Brad a simple bit of advice.......you might want to consider an extra gearbox adjuster on the left side of the box as well.......the engine will have a huge amount of torque over a stock Comet engine, and the gearbox can and will shift........don't be tempted to run the belt too tight, as the heat from the engine and box, also the clutch outer pulley will expand with heat.......this will make the belt tight and make gearshifts and finding neutral more difficult, plus the load on the bearings not good.........Check also your final gearing........the engine will easily pull twin like gear ratio's.......if you have a good choice of rear sprockets then that should be fine........Twin spark ignition on the road using 95 or 98 fuel run about 26 degrees max advance........we tried 28 and could make the engine ping quite easily on 95 fuel........All good fun, looking good.......Cheers.......Greg.