First of all, if you go with a longer or shorter rod, you will more than likely need some machine work to the crank, block and piston. Second of all, if you go to long, you will hit the head and if you go to short, you will increase your combustion chamber size and possibly smash the piston into the crank, hence the serious machining.
I have Eagle Forged Rods and J/E 8.5:1 Forged pistons sitting in my room.
I am waiting to get all the pieces to my custom turbo kit and then I am gonna have the head Ported and Polished including a 5 angle valve job for $500. I will most likely have the engine builder put in my rods and pistons while the head is getting worked on.