In Bill Gately's race motor, rod length ratio would be of some consideration, but let us not forget that we're talking of street bikes here.
While shorter rods do increase cyl. wall loading by the piston, at lower rpms it is not a problem. Standard rod length in a small blk. Chevy is 5.7 inches (144.78mm for you Imperially challenged folks), but, when Chevrolet designed the 400 small block, they kept the piston compression height the same as the 350 and shortened the rod to 5.56 inches (141.224mm).
For a street motor, this short rod is just fine. Now, when hot rodders want to turn more rpms, such as in a 400 Chevy bracket engine, they usually go with the 5.7" rod and custom pistons. I worked for a place (Performance Chevy Products) which had its own dirt circle track "late model" with a 434" small block. It had a 4 inch stroke(!) and used a custom 6 inch long rod. The compression height was 1 (one) inch even!! That put the center of the pin one in down from the deck. In fact, the engine had Wiseco pistons with just a compression ring and an oil ring, no second ring. And, there was a special machined aluminum pin button with had grooves in it for ring support over the end of the pin.
Obviously there's no need for this in a street engine, just as there's no need for a longer rod, or even stock length rod, in a late model Bonneville engine.
Now, as for those 318/340/360 Mopig, er, Mopar engines making more power than the 327/350 Chevies, I can say as a Mopar fan that it just ain't true (usually). The limiting horsepower factor for the Mopars is the cyl. head. I know, I ported a couple sets (both 318 and 360 iron) for my son's Duster motors. I've also ported way too many Chevy heads over the years......no comparison - Chevy (sadly) wins. The W-5 Mopar heads are very nice, though.
