Mike Maier was quoted in the current Sportscar on his best advice for deciding on "upgrades". His biggy was that you are the best judge of what fits your driving style. Based on your driving the car, then you can target a modification.

There are some really big dollar items that are a very individual decision. Wheels and tires are amongst them. Tires and road condition are going to be what effects everything else.

Definately one approach is to simply work with one of the firms like Tony posted and include in the budget tires (and if needed rims for those tires). Decide if you'll be using a drag tire for trips down the track and add that in too.

The low buck approach is to work from the factory handling package. For an E-body that means larger t-bars than came with your 318 base package, a front sway bar AND a soft rear sway bar. The magazine testers from the period (reprinted in Brookland Books) were not happy without the rear sway bar (commenting on E-body only here). Depending on your roads and tire choice, the largest factory t-bar is the minimum. Stickier tires, grippy - smooth roads, feel confident to going larger on both t-bars and front anti-sway bar.

For the low buck brakes you can go factory disk setup and some good pads, or try out some really good shoes on your current drums. For shoes, I still prefer semi-metalic; although I wouldn't hesitate to use Porterfield's street lining or something from Rochester Brake and Clutch. Both can arc the lining to the drum. Even if you just keep the rear drums, same applies.

Don't forget to budget alignment and some decent, non-adjustable shocks. Parts store shocks or Bilsteins or such.

The low buck approach will leave money for future changes you want to try after driving. It might even leave money for some track time or a performance driving school like Evolution Phase I. Lots of fun and a can 'fix' some things without changing any parts at all.