yeah, 35 h might help a lot with the noise

(actually, 3x the time also should show significant quality improvements, already)
Not too easy, I know, but what's about making the text less uniform? If there is any chance, to do so, you should make some of the edges frayed out

(the ink doesn't suck in the paper, uniformly)
even harder (I guess) would be to add non-uniform letters (which human can write that uniform)
a bit less hard, you should add a slight bump map, that shows the pen's peak's stoke

(you need to find a way, to give it something like a blend of a sine and a gausian gradient

)