Barring anything unusual, if it turned over before, then it is most likely you are doing something wrong today. Check the old main bearings and see if you can get a size. They are stamped std, .010, .020 to denote their undersizings. This way you an confirm you have the correct bearing.

If this drags on too far, you can get a black sharpie pen, and color in the bearing surfaces, and then assemble them one by one, rotating them between each cap install. The sharpie will leave a telltale where the rubbing is going on, and maybe give some insight was to what the issue is.

Brian
EFI-Unlimited