There’s a whole bunch related to intake swaps answered here
http://67-72chevytrucks.com/vboard/s...d.php?t=768531
I’m not sure if it was mentioned in that thread but the LQ4 cylinder heads are cathedral port. The LS6 intake is cathedral port as well but the LS3 is rectangle port. The are spacer kits out there to adapt rectangle port intakes to cathedral port heads but it’s generally not worth it (intakes are fairly inexpensive) unless you’re adapting something like a rectangle port supercharger to a cathedral port cylinder head.