op amp big muff tone stack values or transistor muff values

[Quackzed]

i'd like to use the transistor muff tone stack values in the op amp version.
i'm building an op amp big muff, which has different tone stack values than your standard transistor big muff.  (r's scaled down.c's scaled up)
i tried it in duncans tsc and it seemed to work fine, i used a Z in of 75 for the op amp (1k was the z in of trans vers.)
so the input impedance didn't appear to be a problem, output didn't appear to be affected , am i missing something?!? 

reason is: i'd like to add a 6pdt rotary switch to it, to change the hi pass cap and lo pass caps to different values for some different tone options (normal scoop, flat, mid hump etc.)
now the opamp caps are .1u and .12u which are relatively bigish caps, and i don't have alot of intermediate cap values in that range, but have alot of 1n to 10n caps and they're alot smaller and i could add 2 in series etc...
its an lm741 driving the op amp ts. and theres no output stage after the opamp ts. will it be too lossy? (seems like it'd be less lossy with bigger r's) ?
so can i use transistor muff tonestack values in an op amp muff?  (top pic is tranny vers.)

[Derringer]

I think it'll be a bit lossy with the transistor ts values.

The one I built, with different mods, got up over unity gain just barely.

What you could do though, is use another 4558 in place of the 741 and just build in an opamp recovery stage.
You could do anything you damn well please with a tonestack then!