well, the only way to get a heavier version is to buy one...I came across a 60lbs at 28 inch ben pearson Strato Jet solid fiberglass recurve at a swap meet, and love it! (I got it for 20 bucks, and its in great condition)...building it would take a lot of specialized fiberglass working tools, as well as a source of 'glass that is thicker than we have normally available today (as opposed to 40 years ago, which is when my bow is from).
I personally think that it's cost prohibitive to make a solid fiberglass bow out of your home shop...Hope this helps,
Derek