OK - Fluke says I need a 2 ohm amp. Does this mean a 2 channel 4 ohm amp will work? Not entirely sure how the amp does the magic of splitting up the load per channel.
BTW: Thanks for pointing me in the right direction, was completely clueless as to where to begin.
Clearly those speakers are wired for mono. From the DC resistance you got, which will be lower than the impedance, you may have three 8 ohm speakers wired in parallel. However it is entirely possible that the system is a 70 volt mono PA system, with a transformer at each speaker. In fact I think this is most likely what you have. You need to pull a speaker and see if there is an associated transformer.
If there is no transformer you need a mono amp capable of driving a load of 2.7 ohms, so 3 ohm stable. That may be a tough find.
If as I suspect there is a transformer at each speaker then you need a 70 volt line amp. These are plentiful and relatively inexpensive and have mixer preamps included for mic, CD and other inputs.
If you can contact the previous owner he may be able to shed some light on how this system was powered and used.
As I said, since it is clearly mono and a parallel system my money is on this being a 70 volt system. You will have to pull a speaker to find out.