The thing is with buying any modified car is always take the spec with a pinch of salt as it will turn out to be untrue or thrown together!!

Look at the whole car and see if the actual car is worth it, you’re buying a car not a spec list.

Check all history, rust is a major issue and there are no specific areas to check, check everywhere

If you move away from heavily modded ones like the one you have seen and start to look at cherished/show cars and then modify it yourself you will end with a much nicer car

Hope this helps