why could early 360s run with 250 plus HP stock?

If I'm understanding his question correctly he is wondering why the LA 360's were rated at 250 horse compared to rated to 230 of the Magnum maybe? If that's the question, the answer is pretty simple.. Carb vs Injection. A decently tuned carbed motor will make more horse than a conservative tuned EFI motor. The EFI motor will make more torque though.

Until just a few weeks ago you were stuck with "canned flashes" for the EFI Magnum. Now that SCT has a full blown tuner available it will be interesting to see how much you can squeeze out of a EFI Magnum motor.