Waterline change with DF 300

[Briguy]

I have twin 115 Suauki 4 Strokes. They run fine but I'm re powering with a single 300 DF Suzuki. I have a Mattson and co full transom bracket. I always felt the 115's were about the max weight the boat could handle at 860# for the pair. (Weight of an F350) My scuppers were marginally above water. One or 2 fisherman in the stern or a full bait well was too much with wet feet.

The new 300 4 stroke is 230# less. So my question is, on a 1979 CC with a bracket, how much waterline will I gain with the lighter setup????