what rods would be better for my build

The KB167s are designed for floating pins. That means if the rods you are using dont have the small ends bushed, you will need to have this done to run them. In the case of the rods you asked about, the 340 rods are bushed for full floating pins. The 318 rods are not. So perhaps with that piston choice, the 340 rod IS the better choice. You'll save a little on the price of re-doing the rods. A 3rd choice is the cheaper lines of aftermarket rods, that come bushed. But, these rods need to be carefully checked and corrected before you install them. For me, that adds $100 to the cost of cheap rods. Going with your 340 rods, resized with new bolts and the bushings replced/checked, you'd be looking at $250 or so.