sorry but Ive been at school , night classes are kicking my butt. Anyway 500 would be fine, but make sure you get a new manifold also get hotter plugs to handle the increase in gas. plus update the Ignition buy getting the Ignitor by petrox, it will replace your points and condiser,unless you wann upgrade and get a new distributor and eletronic box.
what wrong with the chicks have you ware them out already are are they getting old and saggy>lol