May I just point you in a slightly different direction for a sec. The A14 has a closer bore\stroke ratio or whatever you want to call it, it's not over square form standard but it makes for a more revvy engine if you were to oversize the pistons and apply all the non stroking related mods to it.

Now it probably wont push the same amount of air through it as the A15 would but it wouldn't be that far off.