There is nothing special that needs to be done to break in a new engine like this.
Use the "break in oil". Set the ignition timing to stock. Use the stock jetting in the carburetor as supplied.
It's best to actually break the engine in by driving it through normal driving cycles.
There is no hurry on changing out the break in oil at all. In fact, don't hurry draining it out. Mileage wise, put 1,500 to 2,500 miles on it. Then when you change it, even though you are going to roller lifters, I recommend treating the oil as if it had conventional lifters using what the cam manufacturers consider an adequate amount of ZDDP in it.
That does not hurt the engine. The issue with ZDDP is that it fouls up catalytic converters in exhaust systems. There should be no "cats" on a Pantera.
When you drain the oil, you will actually see the ZDDP in the oil since it tends to be a mixture and will seperate from the rest of the oil and float separately. It does not go into "solution" as many expect it to do.