360 LA installing Promaxx Aluminum heads

The engine is a 361 with an actual calculated 8.5:1 compression ratio. I upgraded to a small cam which is essentially the same as the stock 383 four barrel cam. I figured due to the low compression I would stick with a hotter plug, hence the 14's. I am not up on the whole ground strap and thread reading. I could drop down to a 12 if that seems better.