Old motor exchanged for newer one. Practical "age" of the rest of the car?

I am currently driving a Ford Fiesta from 2011, now my Aunt has offered me to sell me her old Volvo V70 from 2007. All in all the deal would be roughly a zero-sum game as I could get about the same amount of money back from my current car, so the offer is tempting due to the increased space (I have 2 kids).

Now the thing is, this car has roughly 300000 km which is a lot and I expect troubles from that but the motor has been exchanged recently because some part broke. The new motor has about 80000 km which is totally fine for me but now I’m asking myself how the rest of the car will fare. Over the lifetime many parts have been exchanged when necessary.

How can I estimate the practical “age” of the car? Can I assume that since the motor is newer the maintenance will be like for a car that has been driven 80000-90000 km or is failure of other critical and expensive parts likely to happen soon?

edit: The Ford has about 80000 km and needed some repairs recently but now it is hopefully good to go for a while. So I am not in a rush to leave it behind but it will become too small soon.

edit2: As I live in Austria the Volvo has probably only been used on roads in good condition except for some holidays of course. But I am pretty certain that rocky mountain paths would have been an absolute exception.