I would like to build a lightened reciprocating mass 425, I will keep the forged crank and the 3.975 stroke, new rods, custom pistons. I have seen that the 455 crank has holes drilled in the rod journals, to lighten the reciprocating weight. Is there a reason that this same machining can't be done to the 425 crank? Does anyone know which is the lightest 7" rod steel available? Any other input? (this was also posted on Tech Editors page, incorrectly)

 

Unfortunately there aren't many aftermarket 7.00 rods available, light or not.
But oddly enough even the Scat rods are lighter than the stockers. Diamond is now offering a nice light forged piston as well, let me know if you need help there.
And yes you can drill the rods throws, all of them. But the ones on the ends will make the most difference in the balance. But make sure you watch out for the oil slots, they run a bit off center.