First thing I would do is dual exhaust.2.25 or 2.5 pipe.
Then richen up the jets or install a small 4 bbl of your choosing.
Getting lighter advance springs in the distibutor will help acceleration.
Running a 160 or 180 thermostat will help it run cooler and make good power.
A cam is not necessary but if you do it go small.400's don't make a lot of low end and a big cam will leave you disappointed.
Finding your rear gear ratio will help you determine the best mods.
A well tuned 400(new plugs,good wires,and distributor work will make a huge difference and give you a solid foundation for any mods.

Nice car BTW.