Outboard pictured is not a long shaft
I am pretty sure the outboard pictured is a regular, (http://www.smalloutboards.com/shaft.htm) shaft Evinrude, not a long shaft. I have no experience with a Mac, but the two sailboats I have had that used an outboard would do fine with a long shaft in calm to moderate conditions, but in a good chop you wanted a extra long shaft or dreamed of an inboard. When you go forward in a smaller boat even in moderate conditions the prop may start coming out of the water. $400 might be a good deal for a motor that old (if it is the right size) depending on condition, as a lot of little outboards spend their life in someones garage and get very little use. Two strokes are lighter than four strokes but use more fuel, are noisier, and make more pollution. Weight is a key factor when your hanging off the back of the transom mounting or removing or even raising and lowering on the bracket (a four stroke usually requires a beefier bracket), not to mention if you ever transfer the motor to a dink.