Baking is not very forgiving. If there was ever a time in your life when accurate measurements were super important it's when you are baking a cake.
When you make a cake, it’s important to mix the batter just until all of the ingredients are combined. If you over-mix the batter, your cake will be tough and chewy because you deflate all the air.
Go with what the recipe calls for. Once you become a bit more acquainted with what each flour does and their purposes then you could start making changes.