Hey Bob, the spraying Brake Kleen into the cylinder is 50% likely to be successful in my experience.
A cast iron cylinder will swallow aluminum chips without worry but these chromed aluminum cylinders will score easily.
For the effort and expense, good idea to disassemble and clean out the bottom end if you are ever in doubt if anything is in there.
I have locktited and epoxied helicoils in for various reasons, however never on one of these motors.
Some of our industrial situations had helicoils in places that had fasteners in and out on a regular basis. The helicoi would often "walk" out and be exposed. We'd cut them off with a die grinder, clean out with spray cleaner and seal it in place with locktite or "crazy glue". Epoxy was reserved for the spots where the threads were likely to leak some sort of gas or fluid. The usual method was tap it out with the Helicoil tap, spray it clean with Brake Kleen or similar, putty it up with the epoxy and ram the helicoil in place. Clean up the coil driver well. Normally allowed 24hr cure time with a greased bolt in place. Never relied on a plug of epoxy to seal the bottom unless it was 2 thread diameters deep or more. Any less will be pushed out by the stud or hydraulic/pneumatic pressure.
Helicoil it, epoxy or locktite it if you wish, and/or daub a little RTV or similar on that stud when you assemble it. You will be fine.
Be more careful in the future, I am now!