holley carb
 

Few questions here first is secondary types, mechanical vs vacuum what are they and which is better. Second what is the thought on a holley 750 ultra double pumper with edelbrock performer rpm airgap with a mopar 360 magnum in a 72 duster. Or any other suggestions on intake/carb

On a street car I would use a vacuum secondary carb..

bully -

Like TV said, the vacuum secondary is usually better for the street since it gives a more controlled/metered opening of the secondaries. Still, I don't like those on a performance engine, I'd rather have more direct control with my right foot.

A 750 on a 360 will work, but how well depends on what was done to the engine. A mild 360 might do better with a 600. The P_RPM is a good choice.

Archer

http://www.moparproshop.com/inc/sdetail/6202/4515
Here's what mopar's got for specs cause I haven't done anything to it

With your 4 speed I'd go double pump 750 for sure.