tacet trouble

[David Bobroff]

I'm replacing a damaged page from a part.  I want to follow the style of 
the rest of the pages.  I want to indicate a tacet movement like this:


\markup {
  \fill-line {
    \fontsize #3 \bold "I. MOVEMENT - TACE"
  }
}

The above works just fine.  What I want, though, is to have the word 
"TACE" it italics.  If I do this:

\markup {
  \fill-line {
    \fontsize #3 \bold "I. MOVEMENT - " \fontsize #3 \bold \italic "TACE"

  }
}

...the rest of the line the spacing becomes problematic.  How can I 
change fonts while still keeping it all centered?  By changing fonts I 
see that I have another separate 'element' which is being spaced out 
across the line.  I tried taking hints from the custom headers section.  
I tried adding \null(s) but the output was unpredictable.

Help?

-David