Not to incur the slings and arrows of angry listers but, go ahead and have
the professional mechanic retorque the heads. By it's very definition,
Retorgueing means (in this isolated case) draining the coolant, backing off
the head nut (one at a time in proper order) and bringing them back up to
proper torque. If a stud is going to break, most likely it will break
anyway. Just don't have at it and try bringing up the torque from its
corroded in place state. Okay I'll admit it, after replacing two heads and
suffering the classic "huffing coolant from the recovery tank" symptoms
after about 600 miles, I retorqued my heads to 40 (!) foot-pounds, (hey,
I'll have to take the SOBs off again anyway so why not? calibrated T/W BTW),
and no more problems of that sort. If the coolant system is being
pressurized by combustion gas, it will either work, or it won't. If it's
leaking on the pavement, this won't help.
HTH
Dave