Take any 55A alternator to any competent shop, or read some of the 12v "bible" type books. It takes less than a half hour to open the alternator, loop out the field regulator wire, and set it up so it can be externally regulated or switched back to the internal as a backup.
We are not primarily on earth to see through one another, but to see one another through
Some people are like slinkies: not really good for anything... but you can't help laughing when you push them down the stairs
Here's a picture of a high output alternator sold for Atomic 4's. Looks like the same footprint.
I note the "ignition protected" sticker, above. Isn't it generally considered a Bad Idea to use automotive components in a marine application? Particularly a marine application where we're talking about a gasoline engine in an enclosed space?
... and I don't know what the risk is on a gas motor.
It takes very little evaporated gasoline to create the potential for a tremendous explosion. I don't recall for sure, but it's something like two table spoons of evaporated gasoline in an enclosed space has the explosive power of a half stick of dynamite, or something like that? It's nothing to mess with.
I prefer gasoline engines, because I've worked with them for... well, for a long time . But in a marine application I'm paranoid as hell.