must undo them and retorque one by one in order as indicated in the manual
highly highly unlikely to introduced shit into the thread as the h/g should still be sealing the galleries
Then theoritically Ed, can you do the same by taking out the old headbolts and installing ARP ones in the same manner ?
If so, consider the job done !!!!
I would guess to torque in stages like 50 - 70 and then 90 (or whatever the ARP instructions say ?
id be happy enough to do that
make sure you follow the pattern correctly though
but dont just guess, as above, follow the instrustions exactly. each bolt also needs to go through a torque, re-torque cycle for preliminary stretch before final tensioning.