I had a Toyota 4x4 with a Turbo Celica motor in it, the problem is it had to be turning 2500-3000RPM to have enough balls to make enough power to blend a smoothie, made a bunch of power after that though.
A big block Chevy makes a ton of torque from about 1500 RPM and up and marine hardware can be bought off E bay for peanuts..
But do it, it would be cool as hell, There are Toyota boat motors and even Toyota boats, there more of the roll bar/towboat type, but might be a good starting point for making big power, I don't know enough about them to know for sure..
GT