The LT1/4 engine loves more RPM, thus a better gear to get it to spin up faster and net quicker 0-60 times. A larger throttle body wont hurt after the gear has been swapped to get more air flow to allow the engine to really breathe in deep. Too large of a Throttle body (1,000 cfm) on an otherwise stock engine will kill your torque.
Reprogramming the computer gives you different fuel/spark characteristics. They can force the computer to hold the injector pulse open longer thus giving you more fuel for a given RPM and load factor.
In all, an engine is nothing but an air pump. The more air you can pump in and back out efficiently, the more power it will make under a given RPM band.
You could do gears, headers, 52mm throttle body, and computer reprogram for under $3,000 and make a significant impact on the 0-60 and or 1/4 mile performance of that car. There is no reason a LT1/4 could not dip into the low 12's providing you could get traction, and or 0=60 in four seconds or less (with traction).
On an automatic car you would have to look into a higher RPM stall converter right away, or all this would not amount to much. On a six speed, the performance difference would be breathtaking.