A taper (log) is the closer, more common taper. I don't know how it's used, you could use a bigger pot lugged to get a more steep curve.
JS
PS: I checked the schem, you are talking about the eq section right? If you use a different taper you'll have the flat response at 10 O'Clock, not nice! You should probably go with a 100k (maybe 200kA but I guess a 100kA should do) and load from the wiper to the lower side with a resistor, choose such resistor so the flat response is at center. You could use a trimpot if you want them to be death center, or choose the closest value and call it a day. You will still miss the center tap which ensures death flat at center detent, but with the trimpot you could deal with that.