How long to machine engine?

You are definitely within your rights to be frustrated and pissed.

My motor took about 8 months. After 5 months I started calling at
least once a week. Didn't make much difference until I started stopping by
and after my 5 minute talk to the owner I would start talking to his main mechanic for about 1/2 an hour. Then we started to see some progress.
Again not much.