Just so I understand what you mean....
You want to be able to turn over the decorative top, not turn it like a "lazy susan".
This isn't so much a hinge that you need, but a pivot that also slides/rolls. As you flip the top it needs to be able to clear the frame, slide to the opposite end of the table and close again with the obverse side now facing up.
So you need 2 pivoting "pins" at one end of the decorative top, set in a channel the pins can roll or slide in.
I'll include a couple of links to hardware that might be a starting point.
I don't know how heavy this top will be. The pins may have to be anchored in the channel to prevent them from slipping out if the top isn't moved square to the table.
This is a simple pivot pin, The ends are set into holes in the edges of the table top, but needs a channel to move..
http://www.rockler.com/product.cfm?page=788
This is a table leaf hinge. It allows a table leaf to be folded out 180 degrees. but you still have to get the top to slide back over the base.
http://www.hardwaresource.com/hinges/FURNITURE+HINGES/Table+Hinges+-+Shelf+Hinges/Flip+Over+Table+Hinge