Well, what do you consider full size? I've done kings that are 95" square.
I'm going to guesstimate that those blocks in the king size quilt are 6" finished.
If you make the same exact pattern, but do it with 4.5" (finished) blocks, you'd get approx a 72" square quilt. That whole pattern is just plain squares and HST blocks. You just have to figure out the color combos of the HST blocks and make them. I would cut the starting squares at 5.75", draw the line, sew on each side, blah, blah, blah, cut on the diagonal, and then trim down to 5" unfinished. Layout the blocks per the picture, sew them together and you're practically done.
You can always add a border at the top and bottom to get it longer to fit a bed if that's what you want/need.