Msi b450m a pro
Ryzen 5 3600
Msi 1660 ti gaming x
Kingston fury x 3200hz 8 gb
Random case with psu 600 w 80+ case
viewsonic vx2458-c-mhd 144hz 1 ms freesync viewsonic monitor
Make sure the Motherboard is the B450M-A PRO
MAX (that one should be compatible with R5 3600)
About the RAM, you will be loosing performance with only 1 stick of 8 GB, if you can either get a kit of 2x4GB DDR4 3200 or 2x8GB DDR4 3200, but try to avoid buying only 1 stick of RAM.
The random case + 600w 80+ PSU sound like a lottery good luck with that. For the parts you listed a decent 500~550w well known brand (Corsair, Seasonic, EVGA) power supply will be a better choice than a random "80+" integrated with the case PSU.
If you need to save some money to get a decent PSU and the extra RAM, you can always get away with the Ryzen 5 2600 or even better the Ryzen 5 1600AF (which usually is around U$90 on Amazon when theres stock).
The rest seems ok.
As
rgd1101 wrote, if you have a question, or you wana share your budget (also will be great to know if you don't need storage), we could make some pcpartlist to share with you. But for that we need the info.