Not with any reasonable amount of work. The A3 sight mounts to a dovetail integral with the receiver bridge, they had to change the receiver forging and machining to accept it.
It would be easier to round up a Lyman or Redfield receiver sight and have the gun drilled and tapped for it. You could take off the ladder sight and, if you liked, put on an A3 handguard to cover the gap.
If you did that to an unaltered 03 the collectors would soon be along to tar and feather you. Supplies are drying up and original rifles' values are not going to go anywhere but up. Bubba gun values remain low. You could learn to shoot the ladder sight and not get them upset.
