Re: Vortec or Non Vortec
Vortec is a better flowing, better designed head, therefore motors with them have substantially higher HP and torque output compared to non-Vortec. Loosely speaking, all 1996 and later V8's have Vortec heads, and all 1995 and earlier do not have Vortec heads. I'm not sure when the other size engines started using Vortec heads. As always, there are exceptions.
This is generally true for Volvo, Mercruiser, and Chevy/GMC trucks/vans/cars...
For more details, Google search away and learn the history and soforth.