So I almost herniated my self taking the cast iron intake out of my C2500. If you have an engine hoist handy use it when working on a truck.
So the weight difference between my factory cast iron spread bore versus my edelbrock air gap intake PN# 7561 is about 32 pounds.
The Cast iron manifold weighs 50lb. Edelbrock PN# 7561 weighed 18lb on my scales.
Now if you went with a different non-air gap aluminum intake that had the lifter valley deck and bottom of the runners cast as one piece as opposed to the air gap that has to separate surfaces for each there the weight savings would be even greater.

How is this third gen related?
Well that 454 will eventually find its way into my Camaro.
Saving 32 pounds of weight or more in the front end of third gen is a pretty big deal.

The aluminum heads I have seen claim an 80lb weight savings over factory cast iron.
So aluminum heads + aluminum intake could be 110lb.
Put the battery in the back, toss the A/C and I think you would be pretty close to the factory front axle weight of a third gen with a cast iron on cast iron boat anchor SBC.

 

A BBC with aluminum heads and intake is very close to the same weight as an OEM SBC with iron heads and intake.

Even with a stripped down race car and my engine is moved back slightly, my car is still nose heavy.

 

So that explains what I saw on the ecomodder forum, but even with the engine destined for a 'maro, the RPM AirGap is still way wrong for your peanut port heads, and Weiand's dedicated intake would give more average power for similar money. I'd return that intake before it's too late.

 

When that engine comes out the only thing those cast iron heads are getting put on is ebay.
When that engine goes into the Camaro, the only thing stock will be the block, maybe the crank and rods too.