I would be very wary of trying to move a magnolia, I'm afraid. They don't like being disturbed, and especially not when they're in bloom - that's a recipe for disaster - sorry.

The only time that you might possibly get away with it, and one as mature as yours, would be when it's dormant.

Agree with Spritzhenry trying to move now when it is in full flower is going to cause a huge amount of stress to a tree that doesn't like being moved in the first place.

And its roots are going to be very big. Sorry, but it would be best to leave it to thrive where it is and plant another at your new home. If you try to transplant it, it will almost certainly die and then it won't be flourishing anywhere. :-(