Well if it's stock '71 stuff it's points fired,most replaced motors wind up with a later style stock HEI on them but who knows after all these years.
It's easy to tell,the points ignition has a coil wire and separate coil,the HEI has the coil built in the dizzy cap so no coil wire.

 

makes sense to me.

 

I would put smaller jets in both carbs... If it ran perfectally with each carb individually then its probably rich with both. Ive never messed with dual carbs but that would be my thinking. Now each one only has to provide half the gas to maintain the perfect Air/Fuel Ratio.