1940 Flathead - Question Re Lifter Tolerances

[Maznblu]

Hi All, I have a question I am hoping someone can help me with. A friend of mine is in the process of rebuilding a 1940 flathead engine which, as originally built, did not have any adjustment for the valves. The current tolerance (I hope I am using the right word) is 5/1000 but the manual we have says it should be 12-13/1000. Is 5/1000 correct? Or should we install lifters that allow for some adjustment? Thanks for your help.