I like the longer rods, on a Chevy the 6.00 rod will keep the piston at tdc a bit longer. I've never seen any really impressive flow numbers on the Vortec heads, I prefer the aluminum ones. We played with 1.6 rockers for awhile, ran them on the intakes for awhile and on the exhausts for awhile. This was many moons ago before we had access to a dyno so I don't have the numbers to back it up, but seat of the pants feel from the driver said that having the 1.6 rockers on the exhaust helped low and mid range....Probably from better cylinder scavenging??? BTW this was on a circle burner that by rules was forced to run cast iron exhaust manifolds, so things could be different with headers.....