I had a 69 camaro with a big block! It went 11.80's on a set of multi leaf leaf springs and a set of CAL TRAC bars they have a web site they are very good. Most of the drag radial shoot out guys on leaf springs run these they work excellent for the street and strip! I would stay away from tracion bars AKA slapper bars! They are not good on the front of the spring they put a lot of pressure on it especially on a monoleaf setup! I would go with a new set of springs or maybe adding a leaf to the existing spring and go with the cal tracs or slide-a-links from comp. engineering
good luck