Welcome to the forum.
If you want a lower gain 12AX7, try a 5751 or a 12AY7/6072.
The 12AT7 isn't a lower gain 12AX7, it has different specs and operation points. Other than sharing the same pinout and dual triode configuration, the two are more dissimilar than similar.
Having said that, there is nothing wrong with trying a 12AT7. It won't hurt anything, and who knows, you might even like the tone.