[tim]

To clerify Leo's coment on the rod length. You need stock length 351w rods 5.956 not 302 rods. As for piston choice, use a compresion calculater with the specific information on the parts you already have ( combustion chamber, stroke, head gaskets, etc...) and try the different piston configurations (+/- cc's) until you hit on one that gives you the specs your looking for.
Tim