I too, have the same engine setup. It sounds just as you had described and smokes when cold.Even with a block heater its still ruff running. The timming was set to 1.07mm. I thought I would just bump it up more and try that real quick and see if any differance. Yes, it did start up faster and seemed to smoke less. After that I checked the actual timming and it was at 1.19mm. Sure it could go more but it sounds so rattly. It runs great with plenty of power and smoke only when floored.
it only quiets under heavy load, it can be fully warmed up and it will still be super noisy.