and yes, Purina All Flock is a fine feed - unless there is a significant cost advantage to the local mill, PAF is pretty much a superior feed across the board.
Without knowing the Met levels, I'd be hesitant to try to "fix" things. Actually, I'm generally against "fixing" feeds at all. Here, its not that Met is absent, its that the levels aren't guaranteed.
The good news is that wheat middlins isn't a terrible Met source. Subpar, yes, but not...