.."possible wrong bolts were in engine"
That is absolutely correct. I may add that for many years in my youth I watched as a lot of folks, including my daddy, did not own a torque wrench or could afford one, or knew anyone that had one to loan.
Therefore I'll guarantee you that many bolts were "under" and many "over" torque.
Its just my opinion but I think I'd have bought a new set of head bolts instead of washers.....
Still, hope all goes well and let us know how things go on getting the broken one out.