You may want to check out my thread
here where I detail out the plans I have for my Tercel. The C15X and C5X transmissions will both bolt up to the bellhousing of your xA, so you have a lot of choices. My plan was to use a C52 from an old Corolla along with the automatic differential gearing from a Paseo or 4 speed auto Tercel. This would give quite tall gearing and give something like 1350 rpm at 45 mph.