Have a look at this site.
http://www.kalmaker.com.au/page2.html
Allows you to remap the GM delco ECU.

I've just finished installing a megasquirt http://www.bgsoflex.com/megasquirt.html on my car and the difference in throttle response was amazing. And they're real cheap and easy to set up at home on you PC. Also there's plenty of tuning values around for chevs to at least get you going.

Carbies suck
Throttle bodies suck harder