Yep. Float length is 75-80% of the fuselage length from the prop to the rudder hinge.

Here's a link to a good article to help you with your setup and selection.

http://www.flyinglindy.homestead.com/skisandfloats.html

Post pics of the plane when you have it done. I have a buddy that flies the Morris profile planes with floats. I'll bet the Magic will be a lot of fun.