Do you have a new case?
Prebuild cases are terrible.
I would get a new case, and the the MB you like. Z390's lots of nice choices.
Look out for the things you need/want. WIFI? How many USB 2 and USB 3? How many SATA etc.
If you don't have any crazy requirements you can go cheap with the g the H310 MSI proe series is 59 bucks.
MSI MPG Z390 Gaming Plus looks pretty good at 134.
I have used the X370 Gigabyte Gaming 5 (selling it this weekend, been a fine board) and the ASROCKS Tachi 370 very good board.
you have a nice power supply and that will provide good clean power and give you plenty of overhead and upgradeability
I have used several cheap boards in the past, and their still running fine, you can't overclock, you have limited ports, but besides that they seem ok. I like midgrade boards personally when I can afford it, but I'm always looking for the BEST value for ME, at the time of the build.
We take a look at the differences between the Intel Z370 chipset, launched in 2017, and the updated Z390 that launched in 2018. What features does the newer version add?
www.pugetsystems.com
Look at the goals, do you just want a PC up and working again, or do you want something a little nicer?
Eventually as budget allows try to get a larger M2 drive if you can. (shameless plug I have one lol), but a larger drive SSD/M2 will help the overall performance of the system.