if you are prepared to fork out allot of money for a new engine than there is no doubt you will get a better result at the end of the day. personally ill try to repair everything just fot the hell of it, and if i dont succeed then its not a problem because at least i tried and most of the time only spent a few $$ at that.
what type of engine were you planning of replacing it with. it would probably be a fair ide to put a 3.5hp or something on there because the new briggs engines are nothing of what they use to be. its much the same story with the cheaper honda's because there quality has dropped due to the competition with Chinese copies. in my opinion the lower end Hondas are no better than the Chinese versions because every single part is interchangeable and probably just the same without the Honda stamp.
regards jay