Take a digital camera and put it underneath the car taking photo's from every conceivable angle, that way you can see things which your eyes can't.
Look for rust around the rear trailing arm pick up points, the cross member under the front seats and the two rails which run from it towards the front of the car. Other areas to study closely are the area where the front antiroll bar mounts the front castor arms and the top arms of the front suspension. One of the those is under the carbs and practically invisible but the other is under the servo's and just about visible.
When driving it, try and feel if the back end seems to be 'waddling' side to side, thats a sign of worn T/A bushes, expect to have to take third to second gear changes relatively slowly or it might crunch. Check reverse as they can jump out of gear.
if it doesn't feel miles better than your B... it's knackered
