'68 383 barracuda fastback - what to look for?

I'm not sure how the engine was mounted; I'll find out when I go and see it. It actually has under-the-chassis headers; but I don't know what make. I was told it also had the big disc brake and large bolt pattern conversion done.

I'll look under the dash to see if the wiring has been hacked and I'll pay attention to the underhood wiring.