Once you buy new hardware store grade 8 bolts and nuts, the CORRECT suspension bolts with the proper shoulder at the head end aren't really that much more expensive and as Mark said above, that shoulder is there for a reason. And you only need four bolts to do the entire front suspension (lower control arms).
If the originals are in decent shape, a few minutes cleaning them up with a wire wheel can do wonders and will work just fine and save you even more money. Unless the bolts are heavily rusted, there's no reason they can't be reused, it's not like they are exactly a wear item. Once properly torqued, the bushings deflect when the suspension moves, the bolts shouldn't move a bit.
Bottom line: If regular everyday bolts were acceptable as suspension bolts, GM would have used everyday bolts instead of the unique shouldered ones they did use. Those unique bolts are there for a reason, as are the unique pinch nuts used as a locking device.