as a back up plan don't let the PA-D45 being a "PA" driver bother you. Depending on price it may remain an attractive alternative. There is nothing more "PA" than my Eminence drivers and they sound sweet.

That bad association with "PA" sound is likely your objection to uncompensated radial horn frequency response. Between the great parts you are collecting and the Pi crossover, I seriously doubt you could get that sound you dread with any quality compression driver which is appropriate for the design.

I think your gonna build a winner!
keep us posted!
Thomas