Not in my book, as unfortunately that hardening process in not guaranted to penetrate equally as deep around each journal and that can make cutting the Crank evenly later on if need be down the road impossible. If you want more ware resistance and the added plus of making a crank stronger then bite the bullet and send / take the Crank to be cryogenicly treated or in a street motor just run it as is because the factory did not nitrite the Crank and the Bearings used had a soft enough top layer to let grit imbed into the face of the Bearing and not chew up the surface of the Crank.
The crank only needs to undergo a surface hardening process if your going to run a hard bearing... If you Stick with P series Clevites, you will be fine. Any Foreign matter/ and even normal wear particulates, from cylinder wall and cam break in, get caught between the crank and those hard bearings, because they won't embed it, and the result is it eats the cast crank alive.
