Piston and con rod dilemma

Agree with Moper that forged pistons and aftermarket rods are good choice for your motor but I still would have some concern over your 340 block which is already bored.

.060 is the largest over bore that pistons are readlly available for the 340 block so checking the bore sizing will be critical in this case to see if you can still use a .060 over piston especially since your current pistons are worn out.