Bad Day, Very Bad day

Solid lifters or hydraulics? If they are hydraulics, and you had 0 oil pressure, you wouldn't have an engine sounding like a sewing machine unless you caught it at the moment you lost pressure. Is the radiator still topped off?

Trying to be positive, you may have two minor problems (I hope).
1) bad gauge, or line, etc.
2) the steamed up oil in the breather could be something simple, but you won't know for sure until you drain the oil. You might have caught it so quick, that the oil in the pan still appears clean on the dipstick.
But the first thing I always want to do on a deal like this, is drain the oil into a clean pan. I use a paper paint strainer, to see if it catches anything. But you motor sounds like a sewing machine, so you are just looking for water, and that will be obvious when you drain it, if there is any there.
If you find some, then I would run a compression test. If the radiator was a little low, you may just have a leak between the intake and the heads, have seen that before on a SBM.