Flame arrestor at passenger side valve cover

[03BlkZ]

Ok gents please excuse my ignorance but I got a question. I am in the process of reassembling my 70 C10 from its restoration and I need to know if in need this guy or not. Looks like a flame arrestor that the hooks to the passenger side valve cover then to the hose and runs back to the carb/air cleaner. What is this actually for and could I just used a breather in that position? My engine is a 350 and will be using the Edelbrock performer rpm intake with the summit 650 CFM carb with electric choke and vacuum Secondaries. Again excuse my ignorance. I am still pretty new to working on older vehicles. Here is a pic.
Thanks!