If you're certain the bend is only on the exposed threads and the prop tips track correctly then I'd leave it alone. Usually a crank bends in one (or both) of two places. The first place is where the threads begin and the second is the machined area in front of the front bearing where the prop driver sits. Either is easy to check without dismantling the engine (other than removing the prop driver) by first putting the machined area into the lathe chuck up against the front bearing. Hold the crankcase and turn the chuck by hand. Any bend will show up by a wobble at the back plate. The length of the engine magnifies any bend. If there's no wobble then lightly clamp the threaded part in the chuck and repeat.

I always straighten them either by hand pressure (you can put some bar stock through the inlet passage for extra leverage) or by using the cross slide to push it over. Be reasonably gentle at first until you get some idea of what force is needed to make an improvement.