Tap Dimensions

I'm making a 7/8-14 tap to make reloading press accessories, so all the dimensions aren't that critical. I was surprised to find that Machenry's Handbook(s) (16th/26th edition) don't provide all of the dimensions that are needed. Is there a reference that will provide either dimensions or equations to be able to size them. In particular, I was curious if there is a relation of flute depth and radius to size, and if there is a core diameter that relates to size. Is the flute at an angle in relation to the axis of the tap? Thanks for the help. nic