Helicoil and stau with stock size bolt?
Drill out an tap for next size up bolt?
At least I didn't snap the bolt like someone I know did once...at the racetrack...trying to fix my crappy bike for an endurance race...at the WERA GNF. ;)
Is the head off the engine? Not that it matters to which repair technique you decide on - you'll generate chips either way. Just be careful about letting any chips fall into the engine, but no need to tell you that.
I think if it were me, I'd heli-coil & use the original bolt. Using a larger bolt means you'd have to drill out the hole in the cap, too, & then there's no turning back. Also, a larger bolt is a stronger bolt & might well apply more clamp load (what would you use for a torque?) which could distort the cap & bind the cam.
Just my humble opinion.
Sorry about your bad luck. Hope it all works out.
Without a doubt, Helicoil. It's a quality repair you can take pride in. And, no drilling the cam cap.
Ok, done this a few times too, here is a trick for you whether you go larger or not, take your tap, and give it a good smear of Lithium grease, as your cutting the threads, the grease will catch and hold the cuttings. as a precaution, try to stuff some rags around the area to help catch any cuttings that get away.