Here's a handy formula that will tell you all you want to know.

(MPH in 1/4) x 17.6 (constant)/ (Tire diameter x 3.14 (Pi) x 60 (constant) x gear ratio.

Your current combo would look like this:

107.8 x 17.6 / 28 x 3.14 x 60 x 4.10 = 5308 RPM


I did this for an old combo on my RR and it helped.