Looking to buy first gen. Need help

I am looking to sell my '00 Tacoma and pick up a late 80's 4runnner. My plan is to put most of the money from the tacoma into the 4runner so I am not too worried about any mechanical problems. What I am worried about is rust. I live in the mid atlantic and I would imagine that every vehicle over 10 years old has some rust on the frame. How much rust is too much? if its only a small amount what can be done about it and what else needs to be looked at before buying.

Thanks for any help