You will never know for sure until he's with the new cat, but I think the fact that he has his little girlfriend up the road is a good sign. Maybe you could note her personality traits and look for the same in your next cat. It would be good if you could see cats interacting with each other before selecting one so you don't get the alpha from a group.

We introduced Tabasco and Pickles into the new house before it had Mini and Jasmine's scent and while they were all insecure about the new surroundings. It was the first time they'd moved so I can't be sure, but I feel it helped them integrate more quickly because they were all in the same 'new house' situation.

How exciting, not long until you leave!