The original intake manifold is connected to the exhaust manifold to provide some heat to keep the gas as a vapor. When a gas mixture moves through the intake, it cools down a little and has a tendency to pool up on the bottom of the intake. This in turn will cause a hesitation when you step on the accelerater. That is why you need heat to the intake manifold.

Getting heat to your intake is typically done with exhaust or water. It depends on what intake you are running.

You mentioned you were going to be running Fentons. The Fentons have a plug in them that can be removed for use with exhaust heat on the original manifold. Several of the venders sell a kit for this purpose.

Getting back to my original reccomendation... a 4bbl intake... These are usually designed to bolt up with the stock exhaust. They get heat the same way the factory intake gets heat. Using the after market adapter plate for the fentons to the stock intake should work on the 4bbl intake.

Some 4bbl intakes come set up for water heat, some have no provisions for heat at all.