Yes possible ,these studs are close to the cylinderwall.
Did you run your reconned engine for an hour and retorqued head nuts after that time with the engine still hot? Its also recommended to loosen cylinderheadnuts slightly before retorqing.
Did you coat the gasket with sealer? (Ford says that it is neccesary)
I did mine with Rolls Royce Hylomar and its perfectly tight.
If there is oil in the cavity between head bore and stud it may cause bubbling at the nuts. Suggest run engine with radiator filled to top and run engine .
If head leaks also in cooling system water will bubble up.
Regarding overheating this is very uncommon unless faulty waterpump or radiator . I use my dexta with a 7ft rotary orchard mower and that's hard work, sometimes the engine lugs down about 500 revs but temp. gauge stays in green area. and the fan is only 2 blade.
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