Aaron–It looks more like a Bar-Primed 1" Gatling to me, but can’t really see it very well, just going by the mouth crimp.
As to wither this is worth $700 or not depends on some things you did not mention:
Is this a Factory Display Board or just something put together by a collector?
Do the cartridges have holes in them for attachment or are they live rounds?
Are they all the same company headstamp?
If it is a Factory Display, then it is easily worth $700 +++.
If it is homemade and the cartridges are live, then again, well worth $700.
If it is homemade and the cartridges have holes drilled in them, then probably not worth much here in the U.S., but might be a good buy if you can find a European collector to sell the cartridges to, since most of them can not have live cartridges anyway.