Call me pig headed, and I could be very wrong, but I still think it's 8!
Maybe
@Diytry1 can confirm/deny where the cables go from the bottom, but this is my guess...
I think the large brown wire at the front of terminal 8 goes to a pump.
Behind there, is a slim black wire. I think this, along with the blue in 7, and a brown? (appears black in photo) in 6, go to the tank stat.
Whatever these wires are, the only other choices for oranges location, appear to be 1, 4 & 6.
But I wonder how the wires came to be this way?
It looks as though the 3 port valve cable has been pulled, but I wonder if any other wiring has been changed, or was the system working properly to begin with?