Don’t believe everything on the internet
Did you mean 0.025"-0.027" maybe ? 75ipm feedrate sounds more like it.
If you start from chipload, then you need to choose an RPM value (somewhat arbitrarily, but a better way is to maximise it to reduce cutting forces), then compute feed rate (as you did)
Here’s my take on the whole thing, including chipload values that sound reasonable to me (and most of the community, since I mostly sourced them from here)
I don’t have values for 1/2" cutter, but somewhere between the 1/4" values and twice that, would seem like a reasonable starting point.
Anyway, at the very very shallow depth of cut typically used for surfacing, it won’t matter much and you can usually go faster than what the equations say, since there will be very little force on the cutter/machine.
EDIT: and for surfacing the community consensus is :
RPM in the 16k–20k range
Feedrate in the 80–100 ipm range
Depth per pass in the 0.01–0.05’’ range
Plunge rate is mostly irrelevant for such shallow passes, any value will do.