Best combo? Possibly not. If you can afford to get faster RAM, do so. with Ryzen 1xxx DDR4-2800 is a good point to shoot for... 3200 may be ideal though. It benefits from faster RAM.
I'm not sure about the 350 series ASRock motherboards Voltage Regulation for the CPU, if its like their 4xx series boards (except the TaiChi)... It might be adequate, but not if you push the CPU.
Your chosen cooler is okay, but... there are better ones in the same class and average price range. (If you bump to a Ryzen 5 2600 or even the 2600X with a 4xx series board, you won't need a cooler unless you want to squeeze more performance out of it. You can also get DDR4-3200 RAM)
AS already stated, using https://pcpartpicker.com/ will help you sort out cost and compatibility too.