Not directly to answer your request but I have a 20 foot 1986 Grady Overnighter which is essentially your boat albeit having a few additional years of experience. I have used gimbal mounts originally for Penn electrics and now for Scotty electrics and also for an Ace Brutus pot puller when pulling shrimp pots. So far no problems; no doubt structurally it will outlast me. One thing, my boat does not have recessed inner walls for rod holders so it may be stronger than if recessed.

You did not indicate why you wanted to make the change but if it is a structural concern take my experience into consideration. You may be wanting to fix a problem which doesn't exist.