Multi-syllable lyrics in "modern" plain chant notation

I transcribed a plain chant for use by modern singers. One tradition is to show a long rectangle solid note head for muti-syllable notes. I could not find such a note head in the Musescore collection of note heads. So I went and strung together 4 "La" note heads in different voices to achieve this effect. This creates exactly the appearance I want, however is not ideal, as the notes risk coming apart when changing the staff spacing. It is also a rather tedious process.

Musescore is great, keep it up! hymn S46 Christ our Passover - demonstration of long note heads for plain chant.mscz

Thanks.

Val