Wize,
The contest is a good example of possibilities but people need to understand that they are PURPOSE built engines... replicating them can achieve similar results but there is a lot of details in the motors that aren't covered and make a big difference in the overall build. The compression and camshafts are also unrealistic, they're just nowhere close to streetable.
You'll see different rod lengths and bore sizes this year, our motors have a compression restriction. I personally generally prefer a longer rod but the proof will be in the pudding when it's all sorted out...
Mopars are a little different, we do quite a few strokers for them but they're far from my expertise.
The bottom line on a build like the 427 is that it doesn't matter. A 6" rod or a 6.250" really isn't going to make a noticable difference, you can go either way. Go with the rod that clears the counterweight and has a shelf piston to match, that's the correct rod length in this equation.
Brian