This absolutely correct. I have done it and I have dyno'd and track tested. It is all about reversion. See the thing is the intake valve won't just flow the same backwards it will flow MORE and A LOT MORE backwards up to about .300". I did this with a set of '596's 11/32" 2.02/1.6 and I saw 96 cfm @ .100"! I thought oh boy am I gonna make some power now---WRONG. Engine was ridiculously cammy and @ 408 cubes made a whopping 461 hp @ 5100 and the worst thing was the shape of the power curve. Nothing down low and a huge wollop @ 4000 rpm. 408 was only 5 tenths quicker and 5 mph faster than my 367.
Leave the 30* seats to the Pontiac and diesel lovers. J.Rob