I wouldn't do the top rail. I am only recommending this for the axis points as that is where ovaling happens. It is a $300.00 AK with an underfolder bayonet that if the receiver becomes trashed you can do as I said previously and demill it to sell for parts or have it rebuilt on a virgin 1.6mm receiver. With the cost of parts kits now you aren't going to lose if it is basically an unfired rifle as you stated.
You haven't posted pictures so I am just going on your description. If you attempt to heat treat more than the axis pin holes you may end up warping the entire receiver.
I mentioned when I posted the links above I was on my way to work. I am not at home and don't have the ability to do all the research for you. Different metal types with different carbon content % take different heating amounts to heat treat. Not knowing the exact makeup of the receiver, I would just heat to a cherry red for the initial heating and then quench in oil. Then heat to the correct temp. for the annealing. There are ways to determine the correct temp with
TEMPILAQFor the ejector you can heat the tip and use a powder to heat treat the tip. I can't remember the correct name of the product but it is essentially
this.. Others have welded the tip also to harden and build up the ejector but then reshaping likely would need to be done.