I have a friend who's 430 was.like that and had a sleeve. Discovered that when we pulled the engine and put a new pan gasket. In his case, the engine is still going fine. If I had a choice I would not want a block like that.
The question is not can it be saved with a sleeve, as it can but what needs to be answered is will the block in that area pass a Mag test and if it does show cracks will the cutting needed to install a sleeve remove all of those cracks !
Yeah if it's not yours leave it. There are too many other blocks out there. If you already owned it then I would try to save it.