2 options on the bolt. Take a hack saw and make a slot for a regular screwdriver. File the sides square so you can use a socket. Temp. solutions only.
I have a love hate relationship with the cork gaskets. They seem to seal better when they're installed perfectly. What's perfect took a whole lot of sets of gaskets and headaches. The stock gaskets with the copper spray seem to be the way for ease, instal and forget.

Les