Tom, the 19mm Canon in LTM is fairly rare, as you know. A reasonable alternative may be to look for the 19mm Canon in FL mount, and pair it with a Canon B adapter (Canon FL to LTM). I have both the LTM version and the FL version with adapter, and tested both out last week to check focus. Using a DAG-overhauled Canon L1, the FL version with adapter gave the same results as the LTM version. Of course, the great DOF of the 19 probably helps out considerably.
Anyway, I believe that the SLR version in FL mount can be found easier (and cheaper) than the LTM version. AFAIK, the same formula is used in both versions of the lens. Lastly, not sure about the hood, but it would have to be quite shallow to avoid vignetting.
Now, latching onto the original finder is the real trick. I ended up buying the FL version after I already owned the LTM version, because it came with a finder. The Cameraquest site says that the finders for the FL and LTM versions are slightly different, but either finder works well with either lens.