318 rebuild/upgrade

I know there are a lot of question of this nature, but everyone's car is unique and I'm a slow learner :thumblef: . I have a 318 in my 74 Duster with the factory 3spd (4spd is at the top of the list right now). I don't know what size gears I have, but the tires are 215 60 r15's and the rear is 8.25. I have a 650 Edelbrock mechanical secondary 4 bbl, edel. RPM air-gap manny, Hedman headers and a 2.5 exhaust system. I am probably going to go with a stock 340 replacement cam from Mopar Performance, but the heads are up in the air. This is my daily driver, but I want to be able to scare the lower school parents at my school :evil2:

What heads would you guys suggest?