Davis,
I have a 1981 200 CCP which is basically the same hull as the 20' WAC. The ride is great for a 20' boat. I have a 200HP Mercury on mine. I would think a 150HP might be a little underpowered but I guess it depends on prop and load.
As far as known problems, I don't know of any. I would just look for normal things such as soft spots in deck, make sure the transom is good. I would go ahead and plan on a new fuel tank if the original is still in there. Who knows it might still be good but it has bound to have corrosion under the straps by now.
Hope this helps :!: