Welcome to Gasser Hot Rods Steve ! ! Well I'm guessing if the springs are new, and your only looking at a mild 350 cui they should be fine, especially if your planning on an automatic. Now if in the future you get the urge to pump up the horse power and add a posi rear you may consider an up grade.
For now how about some pictures of your project. You can start a project thread so we can watch your build or mods.
The springs should hold up fine if they're new. Might need some assistance from traction bars of some sort to avoid wheel hop. Even slapper bars will help, if the snubbers are set close to the spring. CatTracs would be perfect, but not sure if they offer them for a '51 Chevy?