1969 Swinger 340 distributor questions

Hi Guys--

I'm restoring a 69 Swinger 340 that has been converted to electronic ignition. I want to put the car back to the stock points system. I have a points style distributor with the following numbers on the aluminum tag that is screwed to the side of the housing. First line says 39. Second line of numbers is 2875796.
What is this distributor from, and will it work with my 340/automatic car?

I have seen other distributor's listed for sale on eBay with numbers like 2875794 stating they are correct for 69 Dart with 340. What is the difference? Are either of these numbers correct for my car? Will it run correctly with the advance curve built into either of these distributors?

Also, my car doesn't have an external voltage regulator under the hood. Should there be one mounted to the inner fender or on the firewall?
I cannot simply trace the wires to answer my own question because the harness has been cut up beyond repair. I have a new harness on order from M&H.

If I convert the car back to points, will I need to replace the ballast resistor as well, and if so, what number do I need to buy.
Sorry for asking so many questions. As you can probably tell, I'm lost!

Please, any and all help will be GREATLY appreciated.

George