I think you would get a LOT more braking power by replacing your brake levers. If you have levers that are set up for turkey/suicide/horizontal extensions, I have found that they don't work as well with them removed (which I think you were right to do). They also are a sign of a lower quality lever. If you want a lot of stopping power, search eBay for a nice set of vintage brake levers. (suntour superbe, mafac, modolo, etc) and get the aforementioned Kool stop pads. It'll be around $30-$60 depending on what king of deals you find.

Then disassemble/clean/lube your center pull calipers. Spend a night doing this and dialing them in, you will be completely shocked and thrilled by the difference.