Best bang for the bucK:
http://www.sdpc2000.com/catalog/2174...-Head-Kits.htm
Vortec heads require a different intake because the bolt pattern is different, and use center bolt valve covers rather than the old standby perimeter bolts. Vortec heads flow better than the best Chevy heads of yesteryear!
For more on Chevy performance, have your son check out Chevytalk.com, Performance Related section.