Question for ya. I'm new to longtail motors and just got a Swamp Runner and a 670 Predator engine. It's going on a 14ft fiberglass boat until fall time when I plan on getting a 14'48 Jon boat. I have found that the long tail and motor have some serious weight as a setup. Have you had any issues with the transom? My transom is 2 pieces of 3/4 plywood with about 6 layers of mat that was epoxied in. I also have 2 2x6 boards cut at 45 degree angles and secured to the floor and transom as a brace.
Oh man that's more than enough. The long tails seem like a lot because they're such work out to run and drive, but compared to typical outboard 4 strokes and surface drives - they're a breeze on transoms. Especially the setup you described - a predator motor with a swamp runner kit (all aluminum) as opposed to a true GoDevil long tail (galvanized steel) will sit and operate just fine on the fiberglass transom, as well as the 14'x48" aluminum transom. Have fun with it and be safe! Always wear a life vest and ALWAYS wear your kill switch.
