Help with buying a new Motherboard and CPU

So I bought this computer 4 years ago.

https://www.neweggbusiness.com/product/product.aspx?item=9b-83-102-104

Two years after I bought a gtx 1070 and replaced it with what was inside that computer. This pc is doing good and my expectations are low. I have some extra money so I decided to buy a new processor.

I was thinking I can buy ryzen 7 2700x for $169. I don’t know exactly what processor to buy. I was thinking I can get ASRock B450M PRO4 for $75. This is the cpu I’m talking about.

So Am I making a mistake? are there any better things I can buy for the same price.

I am a noob when it comes to these stuff so feel free to criticize or educate me.

Thanks in advance.