If you specify you only want woven shirts and not have different weights/types of fabric you shouldn't need to mess with any kind of fusible interfacing unless the shirts are really threadbare. I did this once for a lady out of her departed mom's clothes and set no such restrictions. It was rather nightmarish and I swore I would never do another one. However, I let her choose a somewhat complex block design and set no limits on what types of fabric I would work with so I had everything from thin cotton housedress material to sweatshirts to a lycra bathing suit that she insisted be included. Had I put limitations on the clothing items it would have been much easier.