If the pistons have already been loosened, I would at least change the rod bolts because the originals are getting too close to "maximum stretch". You will then have to have the rods reconditioned after replacing the rod bolts or get new rods. An overstretched bolt will eventually break.
However, the new rods do not have oil squirt holes for the cylinder bores like the original ones did. I like the squirt holes in my rods if I have a choice.
As for the rods/pistons. You can use what ever rods you have, you just have to order the correct pistons for the type of rod you are going to use, press fit or floating. If you are going to get new rods and pistons, pick out which pistons you like best and find out if they are floating or press fit pins, then get rods to match. If you recondition your old rods, get pistons made for that type of rod.