With the bit broke off in there your only real option is to remove the timing cover and try drilling from the back side.
If it were me I would tack a nut on the front but you need to find someone good with a mig. Might be an option on the back side too if there is a little sticking out.
If it were me I would tack a nut on the front but you need to find someone good with a mig. Might be an option on the back side too if there is a little sticking out.