I am so sorry for your loss. What a wonderful way to remember him though. I just finished a tshirt quilt and the main thing is to use iron on interfacing on the backs of the tshirts. you can either iron on before cutting them or after...I prefer after and cut to fit. Also, if you don't want to do tons of math, measure and write down all your design sizes...then cut all tshirts to the largest dimensions or peice the smaller designs together to make it the same size as the largest dimensions. This way you will have all the same size blocks to work with and sashing is easier. Good luck.