Starter torque is lost in the diminishing outside diameter of the armature.
That can happen two ways, wear of the brushes against it, a rebuild that cuts the armature smooth on a lathe.
With a full armature, there is rarely a problem.
Solution: a new "high torque" starter OR an ignition that retards the advance at start.
Both the Motorcraft and the Pantera-Electronics do that.
Given the choice between the two, I settled on the Pantera-Electronics simply because it is the only ignition that I know of that fires a fouled spark plug and will clean it up while running.
The Motorcraft and MSD do not.
I have an Accell starter on my Pantera. A Tilton race starter on my 347 in my GT350. Both work fine on hot engines.