I disagree.

One drawback is the expectation of performance increases.

I ran a 400 with a set of 46's and a 4 barrel over a set of 5C's. Yes, it ran better than the 8-1 5c's, but not as well as it would have with a set of larger valved 48's, 12's 62's, 16's or 670's.

Pontiac did have engineers working on this.

And the others..Pontiac could have saved a ton by using small valve, pressed in stud heads on all their motors, but did not. I know of one large valve pressed in stud head..061 1967 one year only..and it was nixed.

Off track, but if there were no drawbacks, Pontiac would have used small valved heads and pressed in studs across the board, even for performance motors. This thought is reversed with placing a 4 barrel on a two barrel motor, but still applies.

So a 500 cfm 400 CI motor with an engineered cam for that application will run properly with a tuned 750 cfm 4 barrel carb and intake..I agree. Pontiac should have applied 2 barrels across the board to save money?

The reason you have carb A with Cam B with CI motor C with Head D is overall HP potential and effectiveness of said combination.

Would you put RAII or RAIV heads on a 350 motor with a 2 barrel carb?

Just throwing out some rhetoric...