Goose going to a 5.7 rod from a 6 would mean that you will need a set of pistons. Going to the 5.7 rods will give you a 1.52 crank to rod ratio where as a 6" rod will give you a 1.6 ratio. The longer the rod the less sidewall cylinder pressure. The 6" rod will last longer than the 5.7's do to the fact of less sidewall pressure. Know the only draw back on the 6" rod is that it creates more ponys on the higher rpm range. A 5.7 rod will give you more low end torque over the 6's. If you plan on turning the motor past 5 grand then stay with the 6's and keep the money in your pocket.

 

or how about unless you revving to 8k and running 8 sec 1/4 miles keep the money in your pocket

new forged pistons, rings, bearings, rods and all that crap will cost well over $1300 for good stuff..

thats half a 12 bolt, nitrous, head work, appearance mods, hookers, crack... whatever..

 

I think that says it right there. If you want it to last and you're running NA then the only things that you need to consider are the following:

Long Rod:
+ rotating assembly is lighter (due to lighter piston)
+ Sidewall loading is less
+ Better Dwell near TDC and BDC
- Torque is sacrificed at low RPM if you use a high lift cam
+ Mean piston speed is less, which gives you a higher redline
- Shorter piston rocks more in the bore because of the shorter skirt, and higher piston ping location
- Piston pin is closer to ring pack (or in it) which is a weaker piston and will burn more oil

Short Rod:
- Heavier rotating assembly
- More sidewall loading
- TDC and BDC Dwell is not as good but
+ short Dwell works good for Forced Induction
- Mean piston speed is greater, so you can't rev it as much
+ longer piston = less piston scuffing as it doesn't rock as much in the bore
+ Piston pin is lower in the piston, creating a stronger piston and one that doesn't burn as much oil.


This is all the info I've leveraged off the guys here in my multiple rod/stroke posts. If it were me, I'd keep the 6" rods.

 

I've scrapped that idea. I have an old friend of mine who suggested that when I first built my 383 that I should've gone with the shorter lenght rods. Me, not being an engine guru, I've decided to seek the expert advise of you guys. And I think you guys helped out a lot in making me understand the question I've originally asked. It all makes sense now.

Although, longevity is important to me, I also realize the multiple variables that comes with modifying an engine. A lot of things can go wrong.
At this point, I'm just going to re-ring my motor, port the heads a bit more, go with a bigger custom grind cam, and call it good.
Thanks you all for your kind responses.

 

I was doing a little research and stumbled over a pretty interesting study that an aerospace engineer executed on rod lenght. I think it was very interesting, and worthy of posting. Rod lenght study...
Hope you get something out of it...I admit that I don't understand everything here, but it's never-the-less interesting...