Final answer:
The tech is least likely to run a rifle brush through the galleys.
Step-by-step explanation:
The tech is installing new oil galley plugs in a cylinder block. The operation he is least likely to perform is run a rifle brush through the galleys. This is because the tech is preparing to install new plugs, not clean the existing galleys. The other operations, run a bottoming tap into the threaded galley bores, apply oil resistant sealer to the new plugs, and apply Teflon tape to the threaded plugs, are all necessary for the installation process.