if you do it while the motor is upside down, most all the shavings should fall off. I still mainatin, however, if you still get very good thread engagement (and its worth checking into!), you shouldn't need to helicoil.
See if you can get an ARP stud kit that has longer threaded studs. People have the same problem when going to studs for the cylinder heads. Too short a threaded stud with pull the threads out.