Congratulations and welcome! Your Alfie doesn't sound like a spook though. It is not unusual for a hound to have negative reactions to dogs other than a another greyhound. If he is at all food motivated, and this is the abbreviated version , you might try taking him somewhere where you can be sure of seeing other dogs. But not get close enough for him to react fearfully. Then as he looks at the other dog/s, give him a fabulous treat. This will encourage him to believe seeing other dogs is a very good thing. Then you gradually get closer and repeat. This works really well in conjunction with clicker training.
Good luck!!