Arthur Dalton's posts on page 1 of this thread are worth considering, especially the first one regarding coolant concentration. I mention this one first because it's the easiest to check/resolve.

I had a head gasket changed out on a 103 motor in May of this year. Temps ran a bit higher and I shared some of the same fears expressed at the start of this thread. I started with the easy stuff(coolant concentration) and sure enough, it was WAY too high. Check out JimF's gadget in the thread below. I used the Prestone concentration tool and Jim's calibration to verify an excessive concentration of coolant.

Coolant help and WaterWetter notice

The garage was apparently in a hurry and didn't bother to pre-mix coolant and H2O which I believe is best.

Arthur's second question regarding the shaving of the head is worth considering too. If it was, compression would be raised and a by-product of that could be increased temps.