My Kohler L600 calls for Champion J8 spark plugs with a 3/8 thread, but, the threads are nearly 1/2 inch deep. Champion H10 (same heat range as J8) spark plugs have a 7/16 thread depth and seem to be a better fit. They reach down into the head a little better, but not seemingly too far. It would seem to me that the H10's would be better. It's not like it is going to raise the 6.4:1 compression ratio to a dangerous level. My thinking is that the little extra bit the plug sticks down can only help igniton. The J8 actually is recessed into the head. Am I overlooking anything?