More cam?

If you are putting a better converter in you can retard the timing of the current cam timing a few degrees. A holley type DP carb will 60' better, if you keep your foot out of it you can also get good mpg.
I agree, the double pumper is what I'd be running

I would go to a larger carb 750 ish
I agree, bigger carb - especially on a dual plane intake