here's a thread from the h.a.m.b. that might give you some ideas, it sounds like you already filled the top with metal but this still might help...
http://www.jalopyjournal.com/forum/showthread.php?t=197551
The problem with the way you want to modify the hair pin is that you are going to need a longer notch in case you are turning and hit a bump, which will not only look bad but also weaken the already poor design of the original hairpins. If your going through the trouble why not just make new...