Welcome aboard!
Best bang for the buck upgrades are an intake and carb, and a new cam.
Try the summit website or catalog and look for summit brand stuff. You can get a double roller timing set for $29 a cam and lifters for $79 and an intake for around $80-100 for an edelbrock (prices are last time I checked on them). If you're near them I'd go check the store out, It's like a car parts candy store, most everything is on display. Every so often I drive the 70 miles to go wander for a few hours
Depending on what year, the later ones (they made them from 1970-1980) had 175hp, I'm not sure how much torque. emissions junk really bogged these down and the cams were way retarded so the first upgrade should be a cam, then a good intake and carb, then headers. Me personally I like a single exhaust system sound better so I'd get 2.5" pipes into one 3" pipe out to the back. or if you have headers with 3" collectors, 3 " all the way out. If you get duals I wouldn't get biggers than 2.5 pipes.
Good luck!