I noticed that many of the appliques are stitched with an on point orientation, so I think it would be best to set the blocks on point. I don't think it will be as difficult as you are anticipating. Maybe some others here can give you suggestions where to look for instructions on sewing blocks on point; I haven't done it myself. The Irish Chain is one of my favorite designs and it should also look awesome with blocks set on point. It's a wonderful thing you are doing with your grandma and I wish you tons of fun sharing this project.