If you would like to keep the concept of the Mk3 sight but would like a finer adjustment and more control, go get a Mk1.
The Mk2 & Mk3 were basically cheap and quick to produce, still gave MoM (Minute of Man) and could be called war time expedients'
You won't regret it.
Mine are not the best, but they are not too bad. I can think of lots of Enfields I'd rather have but instead of constantly striving for more, sometimes it's good to be satisfied with what one has...