Doesn't matter which one of the 'blown' P-51D canopies you fit, or P-51H if you want to go that path, you will get potential for distortion in the 'blown' plexiglass. A simple solution would be to make a cutout in the plexiglass in the area in front of the camera lens, and insert a framed segment of optically flat glass. It would limit to some degree the offset angle the camera mounted behind the pilot's seat could be placed, but it would resolve the potential for distortion. If they wanted a recce version of the P-51H, they would have found a way to make a camera or cameras fit in locations that produced good photography and allowed proper access to the camera(s) for servicing, etc.