The stock brdige is specified as string-through, I have to assume you don't have any holes to go through in the bridge which gives two options: change bridge or drill holes.
Being that's a unique bridge, you may have some trouble finding an exact match that's already configured for top-loading. Also, if you change the bridge you will have some screw holes exposed and possibly a dent in the finish. Sooo, if it were my bass I would leave it as-is, because I have a bass that goes both ways and I'm not convinced it makes any difference.
If you really want it top loaded, think about the steel thickness - some of those bent plates are thin and are better off as string-through. While you could just drill some holes, maybe a machinist could notch it out for speed loading (see image from Hipshot) and replate it. That would likely cost the same as a new bridge. And, IMHO, top-loading is much more fun when the bridge can be speed-loaded (this also helps preserve the coating on Elixirs, Black Beauties, and the like).
