I stopped by and spent an hour or so with the seller this morning.
The ad can be read several ways, but in person he's quite clear that whilst the car is road-registered it was originally built for hillclimbing, and he wants to sell it to someone that understands this.
The backstory seems to be that it was built up in Europe quite a while back, and moved to the USA some time in the last ten-ish years. It spent some time in Florida, then LA, and it's been in SF for a while (at least 3-4 years). As a consequence of changing hands it's not clear exactly what the deal is with the engine; I suspect someone that knows them better would be able to ask more right questions, or recognise the head/manifold - I spent some time last night googling pictures and couldn't come to any specific conclusions.
In general, it looks to be in pretty good condition. There's a little surface rust on a few spots under the body, and possibly in the roof at the top of the A-pillars (no headliner in the car), but I didn't see other evidence of rust anywhere on the car.
The underbody looked clean; I poked around under with a flashlight and up in the wheel arches and whilst there are a few odd holes in the floor pans where things were bolted or screwed in once and then removed later, they seem clean and solid. There weren't any obviously crumpled-and-straightened areas that I saw.
Wheels are 13x6, the spare doesn't match (as in the photos). I couldn't pick out anything specific about the brakes; the rears look like the original drums, the fronts weren't visually remarkable (didn't look like the pictures of Girling calipers I've seen).
Overall the engine bay wasn't remarkable; some wiring could use cleaning up, and there was a little oil on the bottom of the pan, but if you extrapolate out the pictures that's about what it looked like.
I took the seller up on their offer of a ride; we'd established at that point that the car was something more hardcore than I was looking for, so I thought this was very generous of them.
This was quite exciting. In a good way; it's been a while since I've been a passenger in a race car.
Clearly whatever's going on with the engine, it makes plenty of power (and a lot of noise; there's a carbon-fibre Remus and a resonator under the back, but there's no sound damping and lots of cabin noise in general).
The suspension actually felt pretty good; I would want new tires and wheel balancing before I could comment more, but SF is well-supplied with potholes and nasty freeway joins and it wasn't a complete disaster. It felt pretty planted on the freeway.
Assuming the tach can be trusted, it pulls happily to at least 8k. The gearing seems pretty short; I'd say it was at around 7k in fifth at 80-ish, which would seem consistent with a final drive set up for going up hills rather than cruising on the freeway.
The overall experience would definitely match "not very streetable", but for someone looking to run something interesting in a historic class, murder a few cones or go up hills quickly it looks pretty turn-key.