offset grinding crank

You will need to rebalance. The amount of weight "hasnt changed", but the placement of that weight has. You need to think 3 dimensionally. Pistons and boring/honing for me ($600+ depending on pistons) are about $100 cheaper than welding and offset grinding, and the balancing work is the same after either. And you can install better pistons, and have a straight, perfect bore. You'll make better power from better ring seal than loose stock pistons and .160 more stroke.