There are several things you can do. As ryoder said, headers and some sort of cold air assembly would help, but CAIs aren't common for that carbed CV.
Shorty headers would be your best bang for the buck (for headers, at least), as mid- and full-length headers aren't going to fit without modification. The shorties will work best for torque in most cases, anyway.
You could also look into a 4bbl carburetor and a better intake manifold... electric fan... free-flowing cats... all of which are available on eBay for good prices. Don't get eBay headers unless the seller specifically states a reputable manufacturer. I have a few friends who have had problems with eBay headers cracking at the welds.
The 5.0 came with fuel injection didn't it? I know that the 90 model CV that had a 5.0 in it had injection, on our departments unmarked(detective car) anyway. Was that just special order or did they just not put it on the 5.7
For the 302s, 1980-1983 or 1984 (can't remember) was carbureted, 1985 (and 1984?) was CFI, which is similar to GM's throttle body injection, and 1986+ was EFI.
None of the CV/GM/TC 5.0s made much power. On a chassis dyno, it only pulls between 120-130hp and 220-240lb/ft at the wheels. The torque peaks out right at 2,000 RPMs. It's very well-tuned, though, because the torque pulls up just enough to really get that yacht moving. I was able to rip my tires loose at the drop of a hat when I first got my wagon.