but I have a question after returning to Civ 3 after a long time away. Is the only way to get historical starting positions to buy the Conquests expansion?
No, you can do it in patched Civ3. (Definitely make sure to update Civ3 with the latest patch, 1.29, if you haven't already!) Open up the world map you're using in the editor. Right click on a tile with a starting position. Click the "Change..." button next to the Owner box, choose the middle of the three options to set ownership by civ, and select the appropriate civ. Rinse and repeat till your map is set up.