I would go with the helper springs like you see on ebay all the time. Bjorn tried a set and they did the trick!

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7971554458

Is just one of the sets I saw when I searched for "helper springs"

Cheap way to get the results with out the ugly shackels or the stink bug look of air shocks... ( I know you don't have to pump them up ALL the way... but it just brings back bad memories! Lol...)

Hope something like this will help. Are they wide enough where rolling the wheel well lip wont work? Or would that help enough? Might check to see how much of the lip is ribbing, and you might be able to roll it just enough to clear?

Brett - 67 Drop Top 455!