[Zeke]

+1 on the bracing. Both hinge mounting point to the latch point is sufficient. Turn buckles or Heim joints. The thing is, measurements should be taken with the doors on. Actually, the measurements should be done with the fenders on and the car sitting on the ground with the motor in.

Having bracing inside the doors would be handy because you could adjust the bracing with the doors on.. But, if there is any work to be done to the rocker panels, the doors have to be off.