Makes sense, I would definitely get it checked before I bored it that much. I am more and more impressed with the A engine as time goes by. Saw a Duster with a 408 run a 10.75 last summer, at 5400 feet! Wiki stated the LA engine is just a lighter version of the early A motor. So LA stands for Light A. Like 40 pounds lighter. They may not take as much of an overbore.
