Help? how high should i make the floor so it will be self bailing

[Steplift 72']

My 83' model was still self bailing with full 60 gallon fuel tank, a 150 Johnson, a 25 kicker, 5 passengers, extra gas, fishing gear, dive gear...... You get the picture. Find a mid 80's model and take some measurements, just get a couple fixed points, some string, a line level and a tape measure. Then the measurements can go from the keel or chine.