If it is not known to be good you
have to assume it is a core and requires a full-on rebuild. That is why it is priced like it is.
You can build one of these, really any 911 6 to nearly any spec you want, all it takes is money and lots of it.
The clear market trend is to build 3.x and larger engines rather than the earlier ones, cost is about the same (or sometimes less in the case of a 2.7L) and you have more power and potentially a longer lived engine once all is said and done. Cost of fuel and oil systems is about the same but be aware any MFI engine can be quite expensive to get sorted.
You would be far ahead to simply buy a known good engine from
@mepstein than roll the dice on this.
I've done a fair amount of research and agonizing here, happy to share what I've learned but ultimately up to you and your budget so eyes open but do what makes you happy.