Good choice - there aren't many cars around with more roomy interiors!
Avoid cars with air conditioning then. The system is a notorious source
of trouble, although thankfully my car didn't have it specified so this
is second hand knowledge.
You will need to search for a little more detail, but the ABS ECU on
certain model years (I think around 94, but you'll need to check) has a
habit of failing. Check that the ABS light in the dash comes on with the
ignition (i.e. make sure it's not been removed!) and goes out after the
car is started.
I am assuming that you are interested in an estate? If so, I think you'd
be better off with one of the 2.5l engines. I have a 2l 20v saloon and
performance is perfectly adequate (better than expected, actually) but the
engine does like being revved to get decent power out. I would imagine
the estates would be slightly heavier and would need a little more power,
but the best thing is for you to test drive a few.
General advice - don't buy anything that doesn't have a very comprehensive
(and preferably dealer) service history. It seems the 850 can be very
reliable and long-lived if serviced according to schedule and using
quality parts. Look for signs that money was spent when it was needed,
not grudged and temporary/cheaper measures taken to "solve" problems.
I'm delighted with my 850, it's a very spacious, comfortable,
thoughtfully designed and well-built car which is also very nice to drive.
I doubt you'll be disappointed!
You may find the following useful;
http://www.volvoclub.org.uk/information-850-70.htm
If you do buy a volvo, it's well worth joining the VOC for advice and
discounts on parts and servicing. They also have a good 850 forum which
you can use without being a member. Have a read of that and you'll see
what kind of problems can arise.
Cheers,
AJ