Thank you very much. I had no idea about the vents. I’ll go ahead and order those gaskets (the caps don’t really have much resistance to them when putting them on). And maybe order a heat shield
I wouldn’t worry about the heat shield. It’s probably just a combination of lousy gaskets and the vents on the caps.
I’ve got headers on my car with the same master cylinder and don’t run a heat shield, the gaskets and pointing the vents toward the rear of the car solved the leak I was having.