[Perkin]

Right, create a new style in the css (or adapt your existing one)

.let3{
  display      : block;
  float        : left;
  margin-left  : 0.28em;
  margin-top   : -0.18em; /* essayer -0.20em pour deux lignes */
  margin-right : 0.0em;
  font-family  : 'Times New Roman';
  font-size    : 4.6em;   /* essayer 3.33em pour deux lignes */
  height       : 1em;
}

Edit: I don't know if you want to change the french comments

Then using

<p class="let">([A-Z])([^ ]{0,20}\s)(([^ ]{0,20}\s){3})

<p class="let"><span class="let3">\1</span><span class="smcpTypeV">\2\3</span>