AA EXP/ BA Gold here. Even on a basic econ ticket, you'll receive your priority group number, in this case, 2 as a BA Gold. Both tickets offer Main cabin extra for no additional charge. The only difference between basic econ and regular main cabin when flying with BA OWE is that once you've purchased the basic econ ticket, there are no changes allowed. And that literally means no changes- not even to change your seat within the cabin. With a main cabin fare, you'd only need to pay the fare difference for a change, or by cancelling you'd get a trip credit to use within a year.

You'll enjoy 3 70lb bags as BA gold, even in main cabin, but sometimes the agent gets flustered on the rules, so you might need to have the website screenshot ready.

And someone mentioned operational upgrades. I've seen the random occurrence of BA status members getting operational upgrades if main cabin is oversold. However, do not expect it- especially if you're flying between hubs DFW-NYC. I'm DFW based and EXP and many times when I fly to LAX or LGA there are 50 plus on the upgrade list and I'm still 7-8 for 1-2 seats available.