Would venture a guess that the new Pentax 15-30mm will be a good match for the sensor (looking at some of Lloyd Chambers crops). The older Pentax FA* primes (31,41 & 77) will be wonderfully nostalgic, and do the trick.The camera looks interesting. But which of the few Pentax lenses are up to the sensor's potential.
Zeiss ZK's.....28/2, 25/2.8, 35/2, 50/2 MP will be a treat. Voigtlander had a crop of chipped PK mounts; 20/3.5 SLii, 40/2 SLii, 58/1.4, 90/3.5 macro, 125/2.5 macro and the 180/4. Curious to see how they match. My thoughts are that they will perform quite well (well maybe not the 20 and 40).
If Sigma and Pentax can mend ways......or Zeiss be lured back into producing PK mounts, then that will be the ticket.
I just ordered two Zuiko OM to PK conversion mounts from David Llado at Leitax for the 90/2 macro and the 35-80/2.8 ED zoom. I am positive they can outresolve the sensor.
Life is good.....for Pentaxians