There is no such thing as a Dynaco PAT 3. There is a PAT 4, PAT 5, PAT 5 bifet, PAS 2, PAS 3, PAS 3X and PAM 1 for the Vincent Van Gogh crowd, but no PAT 3. Panor made PAS 4 or some such hokum as well.
The answer to your question is dependent on the output impedance of your sources, and most sources in common use today will not have any issue working into 100K or 250K loads. So it really doesn't matter.
All of the PAS preamps came with 250K standard and working into the lower load would not change the RIAA, but might roll off the bass a hair.
For what it's worth, I use a 100K Alps pot on my PAS3 and it works fine, my PAT 4 still has the original pot and it works nicely as well.
If you would like to hear a large improvement in the PAS, bypass the tone controls and filters, particularly that horrible blend thing. Beefing up the power supply helps a lot as well. And the mod that subs the LED for the light bulb made my trannie run cooler. YMMV and good luck.