185 3.0 top speed

I have a newly rebuild 3.0 that doesn't seem to have the top end it should I'm maxing out at 35mph gps at 4200 rpm with a new 14.25x19 black max prop. Freshly rebuilt carb, it idles smooth, has good compression, timing is correct and doesn't stutter. I've ordered a new cap and rotor. Seems like...