I got mine off of
Amazon.
I've only used it on a 7D where you don't have the aperture lever issues. On the 7D I have played around with "A" and "M" lenses. Both have to be used in stopped down M mode on the Canon.
I found using LiveView to incur more accurate metering and focusing. The 7D tends to overexpose with this adapter.
Unlike the M42-to-EOS adapter which pops out like any bayonet lens and makes changing M42 lenses easier, the K-to-EOS adapter works just like the awkward M42-to-K mount adapters. Since you are using only one K-mount lens it shouldn't matter.
I used to own the 28mm shift; it's serious. Now I have the Canon 24mm TSE which I enjoy using on a 5DMK2. Be sure your friend uses LiveView, it makes a big difference.
M