As to lenses, 8x10 is getting close to the territory of 1:1 macro for a head shot (not quite, but if you're framing tight, it is). At that point, the old saw about focal length goes out the window, because getting into macro territory with the bellows extension of 2x focal length changes the effect of the lens. Some of the greatest portraits of the 20th century (think Yusuf Karsh, George Hurrell) were done on an 8x10 with a Kodak 14" (360mm) Commercial Ektar. There were tons of soft focus portrait lenses made in the first half of the 20th century in the 400mm (16") range. I have a 16" (405mm) Kodak Portrait soft focus lens that I absolutely adore on 8x10. Bear in mind whatever lens you use, be it a 300 or a 360 or a 450, a tight headshot can be 1:1, and even a loose headshot (head and shoulders) is going to require at least 1 stop exposure comp for bellows extension. The tight headshot will be approaching 2 stops. Combine this requirement with the general "slowness" of larger lenses, and fast film (400 speed) is your friend especially for natural light photos. Grain is not an issue on 8x10 film - you won't see it unless you start doing 40x50 inch prints. And even then maybe not much.