You might want to consider a morus nigra mulberry, instead of Pakistan. I think Pakistan is yummy, I had a tree, but it was blown away by the flavor of my Noir de Spain. Many people think black mulberries are in the top 3 best flavored fruit, I describe it as a cross of sweet ripe blackberries and zinfandel wine. Plus Pakistan harvest is only about 3 weeks--morus nigra fruits from June through September.
Here is a nursery list

http://www.whitmanfarms.com/category/allplants/edible-plants/mulberries/page/2/

He said he wants a fast growing tree morus nigra grow very slow. I think your original choice is a good one also consider vigorous varieties of fig like panache or mission.

Thank you for your replies, and for the information. I'm going to look into the Noir de Spain. Ideally, yes, we'd like for the tree in that location to be fast-growing, but I'm willing to consider another location for the other tree if its fruit has a better flavor and longer harvest season. In that case, I would put a tree other than a mulberry at the center of the yard. Could you say what the growth habit of your Noir de Spain is, please? The other location I have in mind is toward a corner of the yard, and ideally, the tree there would be smaller

Here is my tree today. It's about 13 years old, and is now growing out more than up, but I prune it every year to keep shade off my other plants
Carla in Sac

Thank you, Carla. That looks beautiful, and fairly big. But it is heartening to see other plants growing in close proximity, so it seems like I wouldn't have to sacrifice all of the gardening area under its canopy. Are those all shade-loving plants?

I have still to hear back from Lucile at Whitman farms, but I will stay hopeful.