Here is good link for info and comparisions of flow for different heads. Yes, the Vortechs will flow more than the original TBI heads!
http://www.sallee-chevrolet.com/fram...ds/Vortec.html

Comp Cams also has detailed info on their site. Very helpful if you want to do the research and get used heads for rebuilding. Good luck!

http://www.compcams.com/