I'm going to suggest something that most people would say is ridiculous...
I would pull the engine and freshen it as required. Why? It's pushing 30 years old, and these engines are well known for valve stem seal issues, and generally poor build quality. The original in my '77 was oiling #4 at 42K miles. More recently, when I built my father-in-law's '77 about 3 years ago, we used a low mile '76 Granada 302. It's not there anymore. Wanna guess? You got it, the seals disintegrated and completely plugged the oil pump pickup. It was so bad, we dug chunks of hardened rubber/plastic out of the oil passages in the crank. Never gave us any sign of trouble until the oil light came on.
It really shouldn't cost a ton of money to freshen it up if it's actually in decent shape, but I would have serious reservations about putting additional load on something that could quite possibly be a grenade waiting to happen.
Low miles don't really mean a lot on cars that are over 10 years old, lots of stuff wears out from age as much as mileage.
I'd say heads, headers and cam kit would be the most beneficial, intake swaps don't usually generate a lot of power per dollar, given the breathing limitations of the above OE components.