HotRods +4 stroker, and some Weisco pistons. Can't go wrong with that man. Huge power difference over the stock stroke. Especially if you get the cylinders ported. Shit and gets, and great for a trail setup. And don't let people tell you it ain't reliable, cause it is. As fas as I'm concerned, it's more reliable than a stock motor. I ride mostly nothing but fast/aggressive trails, and it works good for me. I'm like Tim "The Tool Man" Taylor, so I have plans for a +10 stroker. But a +4 doesn't require any case machining. Put it in, and go.............
Remember, if you get it stroked, you need to at least get the ports cut 2mm's up and 2mm's down, and have the head machined so the pistons don't smack it. Or, you could just get a spacer plate, to avoid the head problem.