Good point about the lip on the strike plate, didn't think of that.

"With a T the tail would have to be let into the door"
I don't understand. I haven't actually seen a T astrigal yet but I
assumed that the tail would be the full thickness of the door, 1-1/8"
or whatever, and that it would simply be nailed into the side of the
door....which, now that I think about it might look a little odd from
the other side. Are you saying that the astrigal is less than the
door thickness and I need to rabbet out the side of the door to accept
it?