Corey dont forget most A15 are old and worn so 78mm bores will change that quickly and not to mention if you are interested there is a Mazda mx5 head that is actually very easy to fit once you have the front plate and headgasket. The pioneer of this conversion will be offering the front plate and headgasket while the rest just falls into place once those parts are sorted. Just something else to consider in case you are chasing more ponies and better optioned head. If you use 78mm Mazda b6 pistons you are set for the Mazda head in the future as its quite a cheap setup to do compared to working an A head.