Ditch the 904 "six-pack" rods, they add mass to an already heavy reciprocating assembly. LYs are better in that they weigh less, use the same rod bolts, which are the most highly stresaed part on the rod.
Aftermarket rods are even better, although you should buy the rods before you deck the block for good squish because they are all a hair shorter than OEM rods. Most are 6.760", one set (Manley?) is 6.765, and stock is 6.768.

R.