Here is the Ramjet intake for Vortec heads.
Merc marine intake for Vortec head use. Used on 305/350/383 marine engines, I run this in my 1997 Vortec 350 reg cab shortbox 2wd truck, runs much better than teh stock truck intake, and allows me to run any sized injector I wish(unlike teh stock truck intake)
Same marine intake next to Vortec truck intake manifold
Same intake in Mercruiser red
Here is the same marine intake with the upperplenum removed. You can see how the runner eopenings are across from the cylinder head intake port it feeeds. the cross ram runners are about 10" long from the opening inside teh plenum to the intake gasket flange.
Inside of Vortec 305/350 truck intake. Lots of injection debris impeding flow.
Scorpion 400 intake, it uses the same tunnel ram lower that is mentioned elsewhere in this thread.