3400 Rocker Arm Bolts
 

While tightening the rocker arm bolts, 2 of the bolts stripped the threads.
It is an 2002 3400 engine, with the 8mm bolts.
Instead of using a helicoil or timecert, could the head be tapped for the 10 mm bolts?
Can the 10 mm bolts simply be swapped, by simply running a drill thru the 8 mm rocker pedestals and tapping the head for the 10 mm threads?
If this can be done, would it be better to tap for an insert for the 10 mm bolt as well to increase the strength of the threads inside the heads?