you can get your stock crank trued a welded and that will hold up to some decent porting, most bang for your buck later would be a 4mm duneport build, you can run that on pump gas no probs should be up in the +70hp region, a lot of peeps roll with a duneport for trails unless its tight all the time you`ll go faster and find it more enjoyable with a less high strung combo
generally once you go beyond bolt on mods and open up the motor chasing power you should sort your crank out so it doesnt grenade