[NovaMan]

You are both correct: a longer rod makes for a slightly lower piston speed.

Let's look at a 454BBC at 6500rpm. With the stock 6.135" rod, the peak piston speed is 7162.2 ft/min. If you go to a 6.385" rod, the piston slows slightly to 7135.4 ft/min. If you cram a 6.535" rod in there, you'll get the peak piston speed down to 7140.5 ft/min. That's less than a 1% difference.