stock are 5/16 diameter. You could use a set of 3/8 with 5/16 ends to fit into the stock lifter cup end, but it is not a direct bolt in and IMO you are fine with a set of 5/16 hardened ones that are at least .100 wall diameter.
For a length checker, you can get them from Summit or Comp Cams. If you have a pedestal style setup, you probably will need shims a well. There are hundreds of tech articles on how to check for the proper length.