rest collision

[Stan Sanderson]

(Lilypond v.2.2.0, Mac OSX v10.3.3)

In the attached example, eighth rests collide with note stems. I'd 
appreciate suggestions about how to make it look better.

The code for the measure(s) is

<bf bf'>8 |
        <<{d8\rest <d f>[ c8\rest <c e>]}\\{<a a'>4 <g g'>}>> |
%%% measure 86
        <f f'>8

The \rest coding was used to bring the rests down from the note heads.

Thanks-

Stan