Unfortunate that the FI was removed. Will be worth a bit less because of non-originality.
The steering is heavy. Always was and always will be. Factory tire pressure recommendations are fairly low too so that doesn't help. The wheel should return to center after driving around a corner, if not some front end service might be needed. There are lots of arms and joints, none of which are grease-able, that may need to be replaced. Also, steering box fluid should be checked if too stiff. Another area to check while your at the front-end is the suspension bushes. The uppers are visible through the wheel opening and the lowers from under the front valence. The rubber should be within the bushing, not squeezing out. A simple way to check is; parked on flat ground, look at the front wheels and any excessive negative camber (wheels tilting in at the top) would indicate worn suspension bushings. Any problems here would help negotiate a better price.
Brakes on an 1800 should be great. 4 big discs, power assist - a perfectly modern system. If the pedal is hard, it's probably seized calipers. They can be re-built. Another possibility is that when they swapped over to carbs, they forgot the vacuum for the brake booster. This car is getting cheaper all the time.
Rust. There can be lots of it. Other than the obvious places on the lower side of the body, here are a few key spots;
1- inside front floor areas above the jacking points (under the car) about 10" in front of the seat bottoms.
2- further up the firewall, on the inside. There is a captive channel that runs across the front of the footwell about 12" up from the floor.
3- engine compartment lips. The area that runs the length of the inner fender, up high near where the relays are mounted.
4- you can lift the L&R outer trunk floor lids to look inside the wheel wells. Good place to look for accident damage too.
Make sure any work was done well. You can get a paint gauge from Eastwood
, or borrow one from an restoration specialist friend to see how much Bondo there is.
Anything else, make sure everything works. Electrical, door locks, window winders. Check the overdrive (shift into it with the clutch like a 5th gear - usually a little slow to engage 1-2 seconds, not instant). Accelerate from stop at full power - any driveline shudder would indicate u-joints or hanger bearing problems. Drive slowly in 4th gear, then floor the gas pedal and note if the engine speed rises equally with the speed of the car. If the motor speeds up before the car accelerates it could be a worn clutch.
Make sure the trim is complete. Some of the chrome/stainless, glass, rubber or plastic parts are no longer available and could be hard to find used. Mechanically they are simple - everything is based on a 120 or 140 series.
Check values on-line. Nice cars get a premium price but it's not in the league of most classics of that era - the Volvo name holds it back. Decent, driveable car, not entirely correct should run 6-8000. Good, original, unrestored 8-10,000 and concours examples 15-30,000.
Don't let your heart guide your final decision.