Where to Start
Wow, think this thread will get some opinion going.
Personally, knowing that a 20 year old might drive it (would be like my wife driving, used to power disks all the way around) I think I'd look at what it would take to make the car stop better and drive better, if the slant is a good running engine and doesn't need to be replaced in the right here right now.
With the increase in traffic we have in today's world, increased amount of idiots on the road, I think anything you can do to make it "drive" better would be the first step. Not just suspension, but alignment adjustments, tires for grip, etc.
But that's just me.