What to look for when buying original type distributor?

[1967RS/SS]

I have begun my search for a distributor that would have came on my car (1111168 7A).  Besides the following, is there anything else to look for or does anyone have pictures as reference?

Aluminum housing
External adjustment 
Single point
Blue color code
Vacuum equipped

[Petes L48]

For comparison, there's a genuine 7B (I think) on ebay, been there for quite awhile at $300 and needing rebuild.  These are actually pretty hard to find, especially when looking for an earlier date.  Correct and unaltered stamping is the first thing to look for.