It's good to learn something about these motors. Never gave the old thing much thought till recently, it's just tucked away with a heap of other motors.

Your engine number is a fairly low one being in the 8,000 block of numbers.
Mine is in the 16.000 block & Ferals engine is in the 32,000 block but the pattern of A13 xxxxxxA remains with that 'A' suffix.
I just noticed a mathematic pattern between the three engine numbers too LOL.

I don't know where these fit in with regards to performance ratings as info is pretty hard to come by for these, but I suspect that is is a 'standard performance' engine & not a 'thrift' or economy engine as was one version of the A14
As for rarity, they are probably the second rarest version of the A series in this country with three identified & verified examples [plus a couple of unconfirmed examples] but no verified examples of the long stroke A13 seem to have surfaced in Australia yet. At least, none that I have knowledge of.

You look after that little treasure now. [or offer it to me at a very affordable price. LOL]

Don't know if I'll part with it. Don't know what they're worth. But hanging onto it until I find the right car to put it into looses me nothing so, we'll see.