Numbers 5 & 7 are hard. I have used the reusable valve cover gaskets from MP or Mr. Gasket. Otherwise, a socket and wrench do the job. As a second tip, the spark plug wires should use a wire loom to hold them away from the tubes. These 1 size fits all header normally can burn the #5 & 7 wires. Short 90* plug end boots help a lot here. Sometimes there not needed, sometimes there a must.
Not all of these headers, manufacturer or batch run by them have the same clearance issues. I like to cut my own wire lengths and use aftermarket wire looks to hold the wires where I want them.
