Starting Dunlop Q-Zone clone... a few questions

[headcreeps]

Hi,
I'm starting a Dunlop Q-Zone clone which will become my 4th clone (after completing maestro fuzz, tube screamer, bsiab2).
Here's a schematic:
http://analogguru.an.ohost.de/193/schematics/Dunlop_QZ-1.gif

-I'm confused about the 500k TP1 in parallel with the 470k log potentiometer. TP1 is a trimpot correct? Where should I set it? Just keep adjusting till it sounds good? 
-I can't find any 470k pots. Will a 500k work fine?
-Any idea where I can get MC33174 and MC33178 samples? I can order them from farnell or mouser but the shipping cost will be 20 times the cost of the ICs.

Thanks guys.

(Edited) - By the way, I'm working on a stripboard layout that I'll post here once it's finished, but if anyone has one ready please post.

[fuzzo]

I got an original by Dunlop, yeah there's a trimpot inside. that's no big deal if you use a 470K instead of 500K.

you can change the IC easily I think .

[PRR]

Chips may be TL074 and TL072, readily available as pedal-parts.

If you re-design as two duals, Aron's 4558 five-pack will fill it up and leave two for your next project.

The trimmer sets the frequency of the peak when "PEAK" is turned to maximum resistance. It tunes below 240Hz, which may be pointless, "all bass"; trimmer sets the extreme to pass the amount of lower-midrange you want to call "minimum". Which is the long way to say "yes".