Re-Powering my 20 footer MA

[ROBCAR]

I am almost done with my 20ft 1979 MA (pics to come). And after all that work, I need to decide what engine and horse power to use. So far, I am considering the new E-TEC from Evinrude because of the weight issue over the four strokes. But HP...I am not sure between the 150 and the 200. Will a 150 hp be enough for this type of boat? Given that I would like to get on a plane without extreme efforts and cruise a decent speed.

thanks in advance for the help......Rob