If it is done, you can live with it. Can be heard as sloppy on startup, but it should take even more clearance to be able to hear it when it is heated/hot. If you hear piston slab in an engine on low idle, it is often from a slack skirt after a seizure, which makes the gap much more than your .007". You can run a hotter thermostat and thicker oil if you have full control on your oiling system, or keep the rpm not too high. Premature wear on a stocker going a high mileage on piston rings due to the piston rocking, but for a hobby car should not be a problem. Let it heat up before pushing it. KB recommends more clearance for marine applications, because boats could be fully loaded before engines are hot, and cylinder walls have not yet grown to hot size. That is not done to optimize on wear, but to avoid a possible scenario giving seizing. You cannot be wrong, it is much worse with too little clearance. My