RE: 5' pt boat
gas would be a great way to go power wise and its easyer than electric to set up in some respects but as said you wont have reverse!!.also gas is messy and you would need quite an expensive engine as it would need to be water cooled as its running below decks so no air flow!!.a zen 260 gpum would be a good motor for scale like speeds and above ,even a homelite would be ok if its water cooled.good tip on the prop shop heres a link to the site!!.
[link]http://www.britnett.net/propshop/[/link]