\xdef\font@name{\csname \string#2/\tf@size\endcsname}%
\pickup@jfont\let\textfont@name\font@name
\xdef\font@name{\csname \string#2/\sf@size\endcsname}%
\pickup@jfont\let\scriptfont@name\font@name
\xdef\font@name{\csname \string#2/\ssf@size\endcsname}%
\pickup@jfont
\xdef\font@name{\csname \string#2/\tf@size\endcsname}%
\pickup@jfont\let\textfont@name\font@name
\xdef\font@name{\csname \string#2/\sf@size\endcsname}%
\pickup@jfont\let\scriptfont@name\font@name
\xdef\font@name{\csname \string#2/\ssf@size\endcsname}%
\pickup@jfont