what kind of colors are you going to use for this pattern? Multi colors? shades of thhe same colors? only a few colors? Also how big do you want to make it? IMHO this pattern does not seem to be really easy to enlarge due to all the small pieces. Perhaps you can add more borders to make it the size you want. If not then to determine how much extra fabric you will need- easy -b just add some to the original amount required . EX- if the original amount was 1/2yd then increase it to 1 yd: 1 yd to 1 1/2yd. That should give you plenty of fabric.
to me this looks like a wonderful medalion quilt that needs to be in the center of the bed with borders framing it or borders as the drop.