Why on earth complicate matters by choosing such a difficult technique? Your project is shallow DOF, 100/105mm is ideal portrait focal length. If it was my project I'd shoot faces @ f4.5 in available light. The film you are currently using will be ideal. BTW, close-up and macro photography are my prefered subjects but I use macro flash units which eliminates many of the forementioned problems. Keep it simple, don't do more than is being asked of you, after all, the next project might be c/u and macro pics.