The way in which quadrature encoder vendors specify counts per revolution (CPR) is often inconsistent. Some specify the equivalent resolution achieved after decoding, which is 4X the number of counts per revolution of an individual phase, i.e. phase A, phase B. Others specify the number of counts per revolution of each individual phase.
My guess is that in your case they are specifying the latter, so the equivalent CPR value for the scaling factors of the quadrature decoder IP is 2,500*4 = 10,000 CPR.
Based on that, let's calculate the velocity scaling factor, which is (1/dT)*(1/(CPR*4))*(60)).
Encoder dT [ticks] = 200,000
That means, for every velocity update, 200,000 FPGA clock ticks at 40 MHz have occured. Therefore,
dT = 200,000 / 40e6 = 0.005 s
So, the velocity scaling factor is the following,
Velocity Scaling = (1/dT)*(1/(CPR*4))*(60)) = (1/0.005)*(1/(10,000*4))*(60)) = 0.3
Based on the ratio to the scaling factor you had, you would get a velocity measurement of 1305 RPM (0.3/0.02*87) based on this new scaling factor.
Let us know if that does the trick.
