360 Casting Number Help

So I have a nice 360 in my 74 Dart sport...am trying to figure out what I have. It has Magnum heads and a bunch of nice parts on it...Demon Carb, MP Intake.

The casting number is this

53020008AB - 360

I have looked on the internet and cannot find any reference to this casting number.....other than an ad for a 2009 Dodge pickup for sale in New Zealand.

Any help on this guys?

Thanks!

Brian