Very late reply to this thread, but better late than never. Instead of just limiting your search for truck 454s, you can also find plenty of boat 454s. Mercruiser is a slightly modified GM truck motor, and there's plenty of old boats with them. Many boat sellers would ditch a motor in order to make a little money out of a boat that's better as a big anchor. The cam in them is different from a street or mud cam. That's because boats run flat out, and don't deal with traffic or lights. They also have to have a marine carb on them to prevent fire and explosions. Street carbs dump small amounts of fuel and that's a bad thing in a fiberglass boat 5 miles from the shore. Of course you'd have to change the plumbing, and also get high flow water pump around, as well as a 5 core rad. The water jackets are bigger in a boat motor, so give it all the cooling you can on terra firma. You can find boat motors with a carb or efi. I just sold my boat because I needed the money, and it killed me to do so. I had a stroked 496 in it, all roller motor, Holley 850 marine carb, plenty of good things done inside the engine, and dynoed at 583 hp. Change it to a street cam and it would easily go over 700 hp. long term plan was to use it in a vehicle and eat the street. One important thing, boat motors are a little taller than street versions. So you'd have to get a raised scoop induction hood. Oh damn, what a shame.....