An A14 engine, with a 77mm stroke will need an 80mm bore to reach 1548cc.
Thats 4mm over standard & frankly, I don't think it can really be done with any guarantee of reliability as the gap between the end pairs of cylinders becomes VERY small & is hard to seal with the head gasket.

If, however, this is really an A15, or perhaps an A14 that has been fitted with an 82mm stroke crank from an A15, then the bore would need to be only 77.5mm to yeild 1547cc. This just happens to be the third [& largest] standard oversize for these 76mm bore sized engines & is a size that is easy to get pistons for & will have no real problems with gasket sealing between the end pairs of cylinders.

If it truly is an A14 engine [with 77mm stroke] & it really does displace about 1550cc, I would be a bit wary of it.
Any A14 or A15 will perk up the KB10 quite a bit, even in near stock trim as you are looking at a nominal 40 to 50% boost in capacity alone & most of it is in the stroke which will yeild a big boost on torque over the A10's short 59mm stroke.
You'll love it.