[sdiy] Vactrol VCF rev 2: help needed

[synth at oldmail.charlielamm.com]

I have a need to build some more of this filter here:

http://www.charlielamm.com/synth/vactrolvcfsch2.pdf

I need to make at least 4 of these.  The last go-around I hand-selected
vactrols until I liked the sound, but when making 4+ of them this doesn't
seem practical.

So I was wondering if anyone can suggest some sort of simple trimming
method so I can use a more random sampling of 5C2 vactrols and still have
it sound good.  I thought a start would be to put a single 250ohm (??) or
so trimmer in series with the diode of VAC2. This is just a guess....

True to the original design goals, I am trying to keep this as
low-parts-count as possible.....

Any suggestions? 

(I supposed I could experiment more with sending the current to the diodes
with some sort of parallel setup.  Then I could have a trimmer in series
with the equiv of R4 for each "arm", but I faintly recall that I found on
the breadboard the setup I have now sounded better (smoother
sweep)...although I can't figure out why.....)

BTW, I am thinking about having extras made as well....it's not that much
more work for me to have 40 PCB's or whatever instead of 4--more money,
but not more work.  If anyone is interested (no obligations, just a show
of hands) let me know and I'll get some extras made up.  I am going to get 
rid of the "sandbox" area of this next PCB rev BTW.

Finally, can anyone tell me where the super-good surplus deal was on
5C2's?  I think this was about a year or two ago....not sure if the vendor
still has any or not, but I figure it's worth a try....

Thanks in advance for any help or suggestions.  

--CL