Alright I did the job with a new bolt and changed the oil too with new GM filter. All is good.
Just for the record when the car died on the freeway/hiway the following was left as codes,
Code Set:
MIL set; Code P0300 ---- Random Multiple Cylinder misfire
Pending Codes:
P0302 --- Cylinder 2 misfire
P0305 --- Cylinder 5 misfire
P0303 --- Cylinder 3 misfire
P0306 --- Cylinder 6 misfire
After the CPS was installed, the car started with first crank and have not observed any issues or new codes. Perhaps I should have left the codes to self clear but I cleared these. I am watching if any new are pending or set. Nothing so far after a days driving yesterday.
By the way if it helps someone, the bolt indeed is M6 and it is 12mm in threaded part and perhaps 15 mm with head included. I got a bolt with different head and it has Torx head that one can tighten with Allen key.
I did reroute the CPS cable away from exhaust manifold towards the left fender/wheel side leaving the Oil filter area. As per Mark's writeup there is slack left with ties holding it in place.
Again thanks to all. I greatly appreciate the help and ideas I received.
Cheers.

PS: If this does not stay as permanent fix I will report back.