Looks pretty solid and the price isn't bad at all if you are looking for a clean and reliable cruiser. I don't have any issue with the SBC swap. Good luck finding 287/327 parts at the local parts store if it breaks down on the side of the road. He could have maybe swapped in a 304 or other later AMC V8, but it isn't like those are falling out of trees either. A little bit of elbow grease and detailing and this thing would be ready to go.
Those heavy-cast Rambler engines were pretty robust. They had to handle running with a factory blower, in some Studebaker applications. If a connecting rod didn't fly through the block, most any repair should be possible. However, depending on what it may be, parts can get really expensive. In the following video, a one of a kind '56 Packard whose internal engine parts aren't, for the most part, aren't interchangable with prior and later models, gets an entire rebuild, because of an engine knock. To me, it sounds like only a collapsed lifter or bent pushrod and that replacing everything else was unnecessary. Since this "mechanic"'s too young to know Old School repair, I'm guessing that he's applying modern throw-away thinking to this classic car. Of course, they don't take us through the entire engine diagnosis and repair. If they can still get parts for this oddball, a Rambler repair should be possible: https://www.dmax.de/programme/cash-fuer-chrom/video/viva-las-vegas/DCB490860007100