There is lots you can do but if you want to make it faster you are going to have to make it stop and handle the speed. I would start with a disc brake conversion, then rebuild all of your steering and suspension, and some sub frame connectors if you're really going to put some horse power into it. Then you can do some basic bolt-ons for more power. Bigger 4 bbl carb, aluminum intake, new cam, electronic ignition, headers, and if you really feel the need etc a new set of aluminum heads.