*Smacks forehead* I absolutely had not considered balance.
Bridge HB - 13kOhm AlNiCo V
Middle P90 - 7.6kOhm AlNiCo II
Neck SC - 7.1k Alnico 3
The humbucker looks to be almost twice the output of the neck pickup on paper. The P90 is actually pretty close to the neck in output.
I wonder how it would balance out with the coil split?
With this sort of thing is it just gain/compression/signal strength going into the pedals & amp that's affected, or would there be a noticeable drop in volume when switching to the neck pickup from the humbucker?