worn key sides

[Dave Nereson]

    I've run into several pianos where the sides of the keys are worn so 
much, or keytops have been replaced, then over-trimmed on the edges, so that 
the key cross-section is now a trapezoid.  That is, the top, where the ivory 
is, is narrower than the bottom.  This makes for large spaces between the 
keys (at the top;  at the bottom, they're still pretty much as original). 
If new keytops were put on, they would hang off the edges, and would make 
the fronts look like a little house that's tapered inward, with the keytop 
as a roof, sticking out on the sides.
    If I glue veneer or other thin wood to the sides, how do I trim the keys 
so that more material isn't added to or taken from one side than the other? 
Is there any kind of putty that can be used with good results?  I don't 
think a disc sander will be accurate enough to sand the sides at exactly 90 
degrees from the key bottom because the gap between the table and the disc 
might let the key tip a little.  Besides, the key front isn't a long enough 
surface to put against the miter gauge to guarantee a square corner.  Is a 
router table with some kind of fence/jig the way to go?  Would it be easier 
to have new keys made?  This is an old, but nice, upright.  Has anybody had 
a new set of keys made (vertical piano -- no backchecks)?  How much does it 
cost?  (I can add the key buttons and capstans myself).
    --David Nereson, RPT