Best Performance Upgrades for Little Money - Here's My Vote

... cast iron 4 barrel intake manifold
OEM 4 barrel High Performance carbs
360 heads
360 exhaust manifolds
Disc Brakes
OEM sway bars
8 1/4, 8 3/4 Rears
Station Wagon rear leaf springs
340 Red valve springs (check them on a tester and you will likely find they are still within spec)
383 440 Red HP valve springs (see above)