Correct hardware

[otis71]

My parts book has bolt head sizes but not the thickness of the heads. I want to put correct hardware on my 41 ULH. When I look at my CP bolts for later year bikes there is 2 head thicknesses. For instance 5/16” bolts have a 1/2” head with some .210 thick and others .249 thick. In general does the 41 use the heavy heads or the thinner ones? From my understanding all bolts should have plain, unmarked heads.