I was told that this late model 5.7 may need a different carb intake if I were to convert it from the stock TBI to carburator.

Is this true? And if so, could someone pinpoint the one I need off jegs/summit?

 

edl-2104 would be the one i would pick for your truck given low cost and low end torque need for a large vehicle. summit has an array of intakes and a search you can put in your vehicle and they will tell you what fits.
your engine is not really late model they made them from 87-95.

 

The '87-'95 SBC heads have the center two intake manifold bolts at 72 degrees, vs. the 90 degrees of the rest of the bolts. The '55-'86 SBC heads had all of the intake mount bolts at 90 degrees. That's the only difference.

Many people have elongated the center bolt holes on each side of a '55-'86 manifold to fit on the later heads. Whether you buy an intake ready to go or modify one of the earlier types is up to you.