It all depends on how much work/time/money you want to invest I suppose. Lets start with the good:
-If he has all the paperwork to backup the engine work and you have someone check it out and it runs well that this is all good
-Having disc brakes up front is a definite plus and not having to worry about braking power is great
-A refreshed suspension is good
The bad:
-That paint (obviously)
-The body looks like it will need more work than just paint but that could just be bad picture quality
It's worth checking out if you planned to get into a project that required mostly cosmetic work. I, personally, won't even think to touch the body because I wouldn't do it justice so when I was looking for a project I found one with a good body on it but needed help mechanically.
In the end it is hard to say from just some pictures and the seller's word... go check it out and see if you think it is a fair price. Just go in with the mindset that you can walk away from the deal without emotions attached and you will always have the upper hand. Take it for a test drive, find a body shop in the area and drive it to them, see what they have to say, then do the same with a mechanic if you're concerned there.
My final 2¢, that price seems fair if it runs and drives well but I wouldn't say it's a deal for either buyer or seller. Try to talk him down a little and be able to walk away. There are other Coronets out there, don't let the seller try to get you worked up into a panic by saying it's a super rare, one of a kind, nothing else like it car (and if he does say that, get the VIN, there are some guys on this site who can check those out and tell you if that's true or not). Now we'll let the true veterans weigh in.