Performance of different engines on a 1972 19' 6" AS?

[Tim/GA]

I am rebuilding a 1972  19' 6" AS and was wondering if anyone has info on how different sized outboards perform on this boat.  I do not even know what size engine would be considered max for this boat.  The guy I bought it from had a 150hp on her.  I am considering a 4 cyl. rather than a 6 for the weight saving but am open to options.  This may be a bit academic in that I will most likely use what I can get my hands on used, at least until the day comes when I can buy a new 4 stroke or better yet E-tec.  I have rebuilt OMCs before so that might be what I stick with, really just looking for some idea of performance based on HP.  Thanks.

[Wilson]

I have a buddy who runs his with a 115 Yamaha 2 stroke.  Not the fastest thing in the world, especially since it has a tower, and I know the thing is full of water, but it gets him around.

[Jason Pepper]

I have a 200 Merc on my 19'6". My wife two kids and I are very comfortable at 42mph in the back country. (Key West)

[scott_gunn]

My 1987 196 has a maximum hp rating of 175 hp.  I have a 150 Johnson on it now, but if I were repowering I would not be upset with a 115.