Just wanted to say welcome to the forum speedy!
I'll defer the questions to someone who has "been there, done that" on one of these engines. But having made that disclaimer it does look like there is a gasket set for it. Probably be one good thing to have in hand along with a piston ring set. As for what else kind of depends on what you find once you dig deeper into it.
Parts and Diagrams for Briggs and Stratton 31C707-0154-E1
Also you might want to checkout the small engine section over at our big brother site: Tractor Forum : MyTractorForum.Com Tractor Forums
There's a number of guys over there that have been through about any engine you can imagine.