Sounds like you lost a rod bearing and may be on your way to more damage. You should always have 10 psi per 1,000 rpm the engine will turn. If you have less than 30 psi at 3,000 you have a problem. The bearing in most cars are a three step process. One of them, the last one, is copper.
The
oil pan is easy to drop in a Cobra and it is my feeling that you need to do that before you run it any more. You could also pull your
oil filter and cut it open to see what it has trapped.
Sorry you are having a problem. Who did the engine for you?