Best way to flush engine after rocker arm failure?

The Trick Flow sheet says 25 Ft.- lbs, which I did.
Yes they are 5/16th X 2 1/4" long
The old set of heads had Allen head cap screws in the rocker shafts. Even with them I do not know if they would even stretch with that torque in aluminum heads.
I am wondering if some sort of lock washer would help? The shaft caps are larger and were the bolt goes through is flat. Just a thought.

A side note that I missed when reading it
TR recommends their stud kit to mount rocker shaft, to prevent stripping the pedestals.