Yes there is 3 diff intakes for the pre-LT and LS SBC the older intakes could be drilled out to fit the middle intake( center VC bolt non-vortec) . The Vortec intake WILL NOT WORK with any of the older style non vortec heads .
I had a 91 Camaro that had a 305 vortec motor that ran in the 12's . I did the vortec head swap long before anyone was messing with them and I spent countless hours on the phone and the net trying to make it work. There was not any after market support at first and there was no TBI or TPI intake out there for the new heads.
set up #1 - stock 305 bottom end , vortec heads ( decked , ported and gasket matched ) , cam, Edelbrock Vortec 4 barrell intake with alunimum adapter for T.B.I. = 13.50's :(
Set up #2 - same as above w/ carb in place of TBI . -- 12.90's
Set up # 3 - Vortec bottom end , everything else the same and added roller rockers and some tuning -- 12.50's
not an expert on the vortecs and it's been a while since I messed with them but if you have questions , feel free to ask and I'll try to dust off the spider webs .....