Here's one way to approach the problem: Look at a quilt the size you're after. Measure the blocks and count how many there are in the quilt. Make whatever blocks you like in that size, plus 1/2" for seams. Do the same for the number and size of borders and sashing. The choices of fabric and design of blocks will be all yours, but the math was done by whoever made the quilt you're basing it on.
If you're too old at 57, what does that make me at 64?!