Lovely quilt. I'm sure it will be cherished.
I'm 5'11" and like my lap quilts to be 60-65" square which allows me to tuck it under my feet and cover up to my neck. If you made the squares each 1.5" or larger, the quilt will definitely be long & wide enough to cover him. If they were 2" squares, it should pretty much cover the entire bed (that would mean it's about 8' x 6').