With your current setup you should see about 53 mph at 9000 rpm, 29 mph at 5000 rpm. What top and cruising speeds are you looking for? Are you doing hills? Also what's the peak rpms you are seeing?
The stock left rag sprocket with the 44 tooth coming from the 10 tooth does 4.4 additional reduction totalling 18.04:1 with the internal reduction. This is all based off someone in another thread saying your 2 smoker has 4.1:1 internal reduction.
You can increase your rear sprocket or jackshaft input, or decrease your engine output or jackshaft output to get better takeoff/hill climbing capability.