383 Broken exhaust stud please help!

The first thing is, don't give up. This what I have done in similar situations:
Using a very sharp punch, try to punch a starting mark for drilling as close to the center of the bolt as you can and keep punching until you have a deep starting mark. Start drilling with a 1/8 bit and keep drilling with graguating larger sizes until the bolt is mostly gone. Then helicoil the hole. You might try a right angle drill attachment for better access.