Regardless of which intake manifold you use, there's an issue to be sorted out as noted by OldBoogie, the EGR deal
Are there any Engine Machinists in here who might know if the Vortec Heads can be drilled to allow EGR flow, or is the exhaust manifold plumbing idea more feasable ?
Vortec Heads do NOT have crossover heat passages, so there is no exhaust to provide to the EGR.
The manifold has a special water passage under the plenum to keep the fuel vaporized
The drawback to Vortec heads on a TBI engine is the need to plumb gases from the exhaust manifold to the EGR valve.
GM recommends using the '96 exhaust manifold (PN 12557828),
EGR pipe (PN 10220275),
and EGR valve (PN 17052693).
As copied from another site, the TBI heating issue from water is addressed by GM with the manifold.
Hangeth-On, there, I am positive that in due time, resolutions to each of these issues will be forthcoming.