I don't know if I can help answer your question, but I have the ZK 1,4/85 as well as the ZK 2/50 and the ZK 2/35. I don't consider myself a street photographer, however I have taken all three lenses out taking photos 'on the streets' and can pass on some observations. I've not used the 1,4/50 though it may be comparable to the 85 in handling, which for me is the noticeable difference between the Zeiss Makro Planar and Planar lenses. I prefer the feel of the Makro Planar lenses, though I do adjust to the different feel of the Planar 85 when I'm using that so maybe it's not really an issue, just something I notice.
For photography on the streets, I much prefer the wider field of view of the 2/35. I like to use this lens wide open, and with the way this lens handles I don't find the manual focus a real problem. Autofocus would certainly improve things when something suddenly catches your eye, but the Makro Planar lenses I have all provide excellent feel when focussing. I am also more interested in going wider and using the 25/2,8 more often when out on the streets. If I could ever find a 21/2,8 even better.
The 1,4/85 has been particularly useful for night time shots of people. The extra speed in the lens means I can avoid pushing the ISO up, so anytime it's dark this is the lens that I would want to use. But the focal length has restrictions and this is where the suggestion of the 55/1.4 might be the best option to give you a wider FoV than the 85, the faster aperture and a sharp lens.
I think there is no perfect lens, but if you seek a single lens to do a couple of things, you will be seeking a lens that provides the best compromises based on what you seek. If you pick up any Zeiss lens, or good quality Pentax lens, you can make it do street and portraiture. You can't make a bad decision here, just one that will have specific strengths and weaknesses based on what you want.
You will notice I didn't mention portraiture. I've never done portraits but there's plenty of info out there and lots of experienced members on this site who can adress that. What I will suggest though, if you intend getting any manual focus lenses then keep your eye out for a focus screen better suited than that installed on the K3
IF the K3 and the K5 have the same type of screens. I can't comment on the K3 of course, but the K5 ees screen from focusing screen.com made a HUGE difference when manual focussing.
So, like I said I don't know that any of this answers your questions, but hopefully the experiences I've had will help and as the saying goes: 'A picture speaks a thousand words'. Accordingly, these links take you to the sets on my Flickr page using the three Zeiss lenses mentioned above so you can see how I've been using and not using them when compared to what you seek:
Zeiss Distagon T* 2/35
Carl Zeiss Distagon T* 2/35 ZK - a set on Flickr
Zeiss Makro Planar T* 2/50
Carl Zeiss Makro Planar T* 2/50 - a set on Flickr (I don't use this lens enough to show you what it can do but I find this focal length handy for adding the environment/context without losing too much detail when compared with a wider lens)
Zeiss Planar T* 1,4/85
Carl Zeiss Planar T* 1.4/85 zk - a set on Flickr
I hope this helps mate, best of luck with your choice.
Tas