NEVER, EVER use a roughing gouge on a bowl. The tang isn't meant to take the stresses from the heavy cuts in roughing out a bowl, and can bend, or break. Plus, a roughing gouge is square across, so keeping the corners of the gouge away from the turning wood is more difficult than with a bowl gouge ground back.
A 5/8" bowl gouge a far better choice for roughing out bowl. Just look at the difference in the thickness of metal between the roughing gouge and bowl gouge.
Please be safe, and use the right tool in the right application.