I have 3 Mopar OEM 400 blocks in stock That would involve several part changes, intake, pushrods, rods maybe depending on thier length distributor if you don't want to use a distributor spacer, cut the crank mains down and possibly the counterweights and maybe some other parts that are not coming to my mind right now. That does eliminate the main webbing problem, if you put some decent main caps on it you should be able to race for long time with no worrys