Hi Toad,
Bear in mind if you change to a Ryzen 3600X and keep the X470 Taichi, you'll need to update the board's BIOS. I'm not sure how much of an undertaking this is, but you may want to consider an X570 board to avoid this step. Asrock has at least one X570 in the same price range as the X470 Taichi, I think it might be called the Steel Legend?
I also think upgrading the GPU is money well spent. If you dialed your RAM down to DDR4 3200 from 3466, you could save maybe $70 or $80, and use that toward an AMD RX 5700 or 5700 XT - a more modern, capable and power-efficient card. Asrock makes one, and Power Color's Red Devil 5700 XT is another highly rated 5700 - I think they are $350-$400 range.
Hardware Unboxed did a comparison video with both 2600 and 3600 with several video cards, and at 1080p Ultra Quality settings, the 580 was limiting fps. You can see how much better a match the power of the 2600/3600 is for the 5700 from his chart at timestamp 13:09 of the video:
I also recommend getting an SSD and Windows 10. You'll love the fast boot times and your system will be much more current and capable in case you should decide to check out other titles at some point. A 5700 or 5700XT should also handle VR at mid-quality settings, and I think VR is just a game-changer for flight sims. Its still early and improvements are sure to come but the more powerful GPU you have, the better off you'll be if you decide to try it.