Originally Posted by BuzzLOL
.. The Vortec heads will help low end torque (1500-3500 RPMs) some if they offer a change from 76cc chambers to 64cc chambers... but I don't recall if the swirl port heads are 76cc or not... just remember the swirl ramps blocking the intake port flow...
There are 2 Swirl Port heads on the 350 engines the casting ending in 191 is 76 ish ccs the one ending in 193 is 64 ccs.
I have yet to do or to see a dyno run where the Vortec head picked up torque on the bottom end without also changing pistons from dish to flat top.