I have an 87 tercel, I picked it up for $200, spent another $300 to get it running well. I wouldnt spend 5k on the car all at once, I would just fix the things that need to be fixed and keep driving it.
BTW with that amount of money and work you could have put a new engine in it with low miles and kept it running even longer.
I dont know... the way I see it, it isnt worth it to spend a bunch of money customizing it or doing anything other than routine maintenance and fixing things. Ya never know when it is going to need a major over hual or be scraped.
Its a great little car though