Simon, the phrase "Clean Up" makes me think of the very similar "Just needs a little bit of welding for MO.T "
Usual problems include a mushroomed end, caused by unprotected hammer blows to the crank end in an attempt to drive the crank through the pinion gear. Here a lathe is a must, to establish any runout or bending. A light cut to remove the damage to the first and second threads and cut a tapered lead is a good start.
For a pulled or crossed thread, the nut trick is a good one which works well, following a needle file to chase the thread back to the end. Cycle thread files are not very common. Starting from the pinion end, the hardened nut will realign the thread after the worst damage has been removed with a file. If you try this, just a single cut on one side of the nut may be enough to allow it to open to pass loosely over the damaged area. Clamp up, not too tight, and work it back down to the end with a dab of cutting compound. It may take several passes and successive tightenings, so keep trying a new nut and the oilpump drive until you are happy with the thread.
Tracy Tools, in Torquay, Devon hold a good range of taps and dies, and are nice folks to deal with.
Swarfy.