If you fix his flaws it becomes your quilt not his. He did this when he was young and it should reflect that. You could even put a lable on it showing when he did it and the pattern, etc so that his kids know. Let it remain his, none of us are perfect at any age. If you had a drawing or a project that he made in school, would you go back and make sure all the lines were colored in the right way and it was all perfect. My 4th son is now 27, in grade school they made self portrait magnents. I was shocked and laughed so hard when it came home from school. He always wore his hair short and spiked, you could see that but when I asked my toe head son why he made himself black, he very innocently said, all they had was white crayons and people aren't white so he chose black because people are black. Today that is on my fridge and is a treasured memory that still makes me smile when I see it.