I'm planning to use a TPIS big mouth intake and runners on my L98 350 so I figured I needed to upgrade my heads. I saw that a lot of you are using Vortec's so I purchased a set. Can I simply tap the required holes in the vortec heads to bolt my TPI intake onto? I've seen RHS heads which have a dual "vortec" as well as "standard" bolt pattern. Would it be possible (or advisable) to drill the required holes in my intake instead?

 

while you can have the holes drilled in either, and get it bolt down, it really requires an intake designed for the heads, becuase of the port shape and angle. basically the vortec ports and the old ports won't line up well.

there are two options, which are really the same, Scoggin Dickey and Edelbrock both make a vortec specific TPI lower manifold. It is a very nice casting and has a good port cross-section as cast, which you can improve, if you wanted to by porting.

it will require an external EGR if you need emissions, and some small touch ups with a grinder here and there to clean a few small clearance issues, but not a huge deal.

while not alot of people advocate the use of this manifold (it's over 300 bucks), it does make a nice combination for a daily driver. Most people on the board will recommend spending that money on a non-TPI intake, as the intake has issues feeding alot of cubes pushing alot of horsepower. This is a whole debate that is not worth starting.

I've rebuilt my 350 to a vortec head, scoggin dickey manifold and SLP runners all ported a little bit, along with the plenum, stock throttle body and a ZZ4 cam. the car is a blast to drive and really needs more stall than the stock converter.

 

TPIS makes a miniram III that bolts to re-drilled vortec heads. I think it also fits LT4.
I have re-drilled my vortecs to the regular pattern by using an intake gasket as a pattern.
The miniram III fits great after the re-drill.
The miniram III to vortec uses a Felpro 1205 or 1255 gasket.