I don't recall if you have your parts yet.
On the gas blocks I use the Geissele Carbon Steel Gas Block sold by ALGDefense (his wife's company): https://algdefense.com/carbon-steel-gas-block.html
The reason I like this particular block is because of the straight forward installation and the fact that it is super easy to pin the gas block so it absolutely will not move. I would recommend this if you have a drill press or know someone who does. Here are the instructions so you can see:
Go to Super Gas Block Instructions and download the PDF, extremely detailed, down to McMaster-Carr part number for the drill bits needed. Good stuff.
There are other gas blocks out there that are already drilled for pinning, but the ALGDefense/Geissele has my vote.