V6 vs V8

VVT allows for higher compression ratio's to be used in conjunction with EFI and the ability for a feed back system to control spark timing and cam timing you can do wonderful things. Add refinements to EGR (i.e. rebreath, a befit added by VVT), computer flow analysis of combustion dynamics, Port flow, and direct injection. Advancements in technology make it better but also make it more complicated and more complicated to modify.
Yep, it all plays a roll! (and more complicated it is). I think the 318/360 magnums could have "yet again" been reworked! When they went from the LA to the magnum, they gained about 50 ponies. I think with some of the "mentioned above" topics, I think we could have easily seen the 5.9 go from, lets say, a magnum to a super commando. I think they could have redone the heads, cam, intake, add VVT, PCM enhancements, and pulled 450 ponies, and perhaps the 5.7 hemi would have never been needed.... then we would have really had some bolt-ons for our classic cars... not that I mind the Hemi, but.... just a thought....