I am looking at 3 President 41 ft., the one that is in best shape has twin 225hp Ford lehmans. The other which is not in as good condition, has what I really want for motors, twin 120hp. Both about the same price. Another one has twin 67 hp. What would the fuel difference between the 2-225 and 2-120 both opperating at displacement about 7 kts.