As far as any imperfections on resin head sculpts: when I used to do any sort of modeling of 1/8 scale resin models, where you had to assemble different parts of a figure together -- to hide the seams, etc., I used "model putty" (it air dries) and can then be sanded down -- very carefully of course -- but it helps to smooth it out as much as possible before it dries so you don't have to do as much work. Much of the time, I use the backside of an X-acto blade to smooth out sections of the model putty.
OneSixthFigures