All that really means is that it was a re-cycled (or perhaps stock) case. Some on here might have a number stamped on their case that has been built up into something else entirely.
Many of us have newer AS-41 engine cases that have no number stamped on them at all - that space is blank - but as Stan and others mention (and you already know) you can't really tell what displacement your engine is without tearing it down and if you're going that far you might as well have a known good engine builder do it and then build it back up (if possible - older cases tend to be warped out of true) into what you think you want.
I would google VW Aircooled clubs in you area and go to their events, ask around for who the good builders are that they recommend and start there. You'll probably get a better build schedule than with the nationally know builders who seem to be backlogged for months and months right now.
And I'm with others on here about where your car came from or was built by. Just get it sorted and straight and as reliable as you can and enjoy it for what it is - a custom build that you've sorted and improved into something to be proud of and drive it.