Well a 400 crank will work take it to a machine shop to have it mains turned down,be sure you get the flexplate and especially the balancer.
Be sure to use 350 rods in a 5.7 or 6in length. Their is another kit I've used a few times that was very affordable is ths one
http://www.ebay.com/itm/Eagle-Sbc-St...cb7401&vxp=mtr
Pretty inexpensive with free shipping after all the machine work and balancing and parts the rotating kit will only be $60-$100 with better parts but I've used 400 cranks several times in the past in 383 builds but I've always used a light to ultra light piston to get the big RPM's quick but back then I was using mechanical flat tappets and had plenty of fun. All together you can build a 383 today using a purchased machine block,with the kit listed above machine you heads,Solid flat cam,carb,distributer for under 2300 bucks. I'd look around for a 383 that is a complete shortblock why because you'll save on average $250-500 but be sure to get through a quality shop that specializes in HP not a POS Foreign and Domestic Machine Shop.