Hmmmmm was just talking to a buddy yesterday about how a gun would react to bolting a 4-5 on no box down the road, then space to height needed... Someone has had to do this on either boat to see....

I would leave the 3a s on the boat, I think you will be happier how it performs. 3a s and 5 s are basically the same strength and moving the prop closer to the surface will probably result in more breakage.

I raised my engines, and drives on my Top Gun with 3A's, they were in the same location that 5s would be. I was able to Plane with 4 Blades and Big Diameter. Little tab. Of course then you run into hatch issues if you are running big blowers, intercoolers, etc

If you don`t want them coming out of the water every 5 seconds and have to constantly throttle then 2" inches below (or more) bottom is my recommendation. .. I actually went faster with that set up vs. even with bottom.

My RH drive is also the red headed step child as you know they break 10x as often due to the weaker design

I Agree totally with the above, Mine were Either 1.75 or 2.25 below. It was set up at TNT in Miami. Anything less and I believe you would be out of the water and probably be difficult to plane in certain conditions. Hard to tell from my picture, but that was the best one that I have right now.

Looks like You are spinning 'IN" and have a notch. I measured this AM and I think the 5 will be about 1-2" below bottom with a 3" spacer