I use the amp with a overdrive pedal at moderate sound level
What speaker would you recommend?
I think you would be quite satisfied with the Vet 10 - they are amazing little speakers. If you want to add a fair amount of volume and usable bottom-end to the little Princeton ... then go with a G10 - an Alnico model will sound a little sweeter than the Ceramic version, and a smooth-cone version will sound a good bit more mellow in the top end ... probably more than you would want with the Princeton.
I would add that 10s for me are always a question of headroom. I do think the Veterans will take pedals better. Especially with a Princeton Reverb.