Mark:
I think you will find both solutions will give you excellent results, I have used both.
Contax 35mm:
Is a bit heavy, and requires a separate piece to use a filter. If you find the lens and use filters, attempt to find the adapter ring that allows you to use filters. Sometimes they are sold as a pair, other times not. The actual lens, has no tilt, only shift. I used it on my various Canon's up to the 5D MKII. The CA is nominal even on full shifts. You should have good image quality at full shifts from around f8 out. Wide open (my lens) was a bit soft on full shift. I used this over the Canon 24 TS-E since the Contax had better image quality of full shifts and was better on CA.
Zork and Pentax 35mm FA:
I quickly moved to this from the Contax, as you can shift up to 18mm. Zork is a good quality piece of gear, and you can adapt it so that you shift the camera body not the lens. This take a bit of doing, however it's possible. I was able to use a standard L bracket and the foot that comes with the Zork. The Zork I used was only shift, no tilt, they may now have one that offers both. If so I would try for the adapter that has both shift and tilt.
I started using the Mamiya 35mm manual focus lenses, and quickly moved to the Pentax 645 35mm FA, you can use it since it has a manual aperture ring (something you don't see much of anymore). With my 35mm FA, I was able to get to 18mm of full shift and still have excellent details, however this was mostly on a 1ds MKII and 1ds. So 16mp was most of my use. When I purchased the 5D MKII, I tried the Zork, but I found that 18mm of shift was not quite a sharp and for some reason I was not able to manually focus as well. Not sure if the 1ds MKII just had a better optical viewfinder or not. However with Live View on the 5d MKII, this quickly became a non issue for me.
The Zork and 35mm FA gave me acceptable shifts from F8 to F16. The best were in the F11 range. The 35mm FA was not that good wide open like the newer Canon 24mm TS-E lens is.
BTW.
I would strongly consider the 24mm TS-E since it's such a perfect fit for Canon cameras. You can shift it to 12mm and get excellent results, it's setup to allow tilt and shift in the same axis, (which is really what you want). No CA, and very good from F5.6 on out. Takes filters with no issues and allows you to stack to filters (thin) without vignetting.
I switched to Nikon 2.5 years ago, and held on to my 24mm until recently, as I just hated to let it go and Nikon's wide PC-E solutions are just not that good IMO on the 36MP cameras.
Paul