[jclark]

That's a bummer, there's to many things it can be.
I don't think it's break-in related.
How does it smoke? when stepping on it or letting off?

Check your compression. Verify that first.
Also you may need to have the system pressure
checked to see if you have a blown head gasket,
(that's my first thought)
if so, have everything checked for flatness before reassembling.
Also checked for cracks (magnafluxed) you could have a cracked
head and not know it. It's going to take a machine shop to check
everything completely and you'll have to tear it down again of course.
Sorry about that.