Although the fall on JPRA is higher, it is no where near as intense as Dudley. The restraints in JPRA are also more "securing" than Dudley (which really has none). I weigh around 200 lbs and still get lifted out of my seat at the beginning of the hill on Dudley (great air time!).
Ah yes........that makes sense. Having never been there before, I thought that they were very similar rides. Well, DS is 43" without shoes, so............
The main reason for the height difference is like someone said, the seating arrangements. Also the incline of the drop on dudley is just a little steeper than JPRA. I wouldnt recommend stuffing shoes unless he is like a 1/4 inch off....safety first. Parks tend to set their height requirements a bit above the manufacturers height requirements....but by how much is anyone's guess....so like I said 1/4 inch below should be fine to try and get by with.