[Ed Wright]

To answer one of your questions Gary, some of the reasons late EFI engines make more power than older engines are the cylinder heads. Improved air flow and improved detonation control allowing higher compression ratios on low octane fuel with out detonation.
The '96 / '00 Vortec trucks heads are so popular on older engines that Edelbrock makes a 4 bl carb intake manifold for them. The ports are high enough a regular carb intake doesn't even cover them. You understand what raised intake ports do, right? :-)
Those Vortec heads make more power than earlier (even "camel hump") heads.

The reason for EFI in late model vehicles is simply emissions and fuel economy.