I would direct you to a useful tool here at the forum
you can find it under "camera" above
it allows you to do a side by side by side comparison of three Pentax camera bodies
Pentax K-5 vs. Pentax K-3 vs. Pentax K-5 II - Pentax Camera Comparison - PentaxForums.com
I have given you a link comparing a K 5 vs. a K 3 and a K 5 II
using the drop down boxes, you can adjust it to reflect the camera bodies you wish.
you should also check out the reviews of the camera bodies you can find under "camera" and in the next section " lenses" you can research your lenses and any other Pentax lens or many 3rd party lenses
good luck
continue to ask questions, members will be more than wiling to assist you.
BTW, shareasale.com/r.cfm?b=889257&u=523490&m=66875&urllink=keh.com offers a 14 day no questions ask return policy check to make sure
---------- Post added 08-04-17 at 17:55 ----------
Originally posted by normhead DxO rates the K-5 higher than the Canon 5D mkIII. But you would have to live with it being a crop sensor. To make full use of your film lens image circle, you'd have to buy a K-1.
yes, crop sensor cameras will not record all the "area" covered by a older lens made for the 35 mm camera. however, don't let that stop you. the lens will still work
Full Frame Sensor vs Crop Sensor: Which is Right For You? Crop vs. Full Frame Cameras | SLR Lounge Full Frame vs. Crop Sensor Comparison
you can either ask more questions or do your own research