it depends on your abilities and how long you plan to keep it. While you have the pan off, check the timing chain for slop and the distributor drive/cam gear for wear. It is possible to change just one piston(in chassis no less!), but all of them are the same age, so there's a good chance there be another in the future. Summit racing does sell single pistons, but you will have to buy a whole ring set even if just changing one.