Plus if it matches the location of the stock intake/header one could upgrade the intake or exhaust without doing the other.
Makes things easier on the budget to do it in steps.
An intake/exhaust combo would be like approach GM took with the integrated 1bbl and 2bbl heads. Combining casting, but this would allow a non-integrated head to be used and have access to the intake ports for lumps and port work.
On the intake side; if it had adapters that allowed a 4bbl, 2bbl, or Monojet; so you could swap the intake/exhaust (and head for us integrated head owners) but leave the Monojet on until a 4 barrel or 2 barrel and air intake is available.
To keep the exhaust output the same I guess means a single 2.5" outlet. However there are 3 different exhaust header pipes, which means you have to design it for one of them. The non-integrated pre '75 L6s had and angled outlet with 2". The integrated head Monojet cars, and the later 292 trucks, had a vertical 2.25" or 2.5" outlet. And the integrated Varajet trucks had a dual 2" exhaust outlet. I guess if you were going to choose one exhaust outlet to cast for it would be the integrated/late-292 with 2.5" vertical outlet. But that means older L6s have to update exhaust to use it.
