340 4 speed crank

I'm in the process of converting my Barracuda to 4 speed. The 340 that I will be rebuilding was hooked up to a 727 so I'll have to drill the crank to accept the 833. I do have another 340 that I'm not using that has a 4 speed crank so am I better off to swap cranks and use the 4 speed crank when I rebuild my 340? :scratch: