Current cam is definitely to big 253@.050 I think the XE275HL would be much better with its 231@.050 I think you can make the current carb work with a good tune.

Even advancing the current cam wont help much IMO, that cam doesn't come into its torque peak until about 4300 RPM Its going to be lazy below that. A first gear swap will help, but more work then changing the cam. IMO, change the cam.