Gpu suggested in reddit (from above post) is 1660 super which is not better than 2060, also that was used GPU suggested but you need new one so I suggested 2060.
Amd RX 6600 is better in raw performance a lil bit compared 2060 so which ever is cheap you can get it. atm 2060 is cheap.
i can't fit 12400F with 32gigs ram and 2Tb HDD. you'll have to sacrifice one 16gb ram if you plan to get 2060(max setting 1080p card) - if you get 1650 (which is a good high-mid setting 1080p card) at 15k you can fit those things.
i gave all the options currently available in your budget. now last decision is up to you. you can always increase extra ram later so for now 16gb should be fine.
final build with 2060 - 55k