David,
A Tayloe detector is of great utility in the "real world" of hardware as a way to get a quadrature baseband signal from a real passband signal. In the DSP world things are much easier!
If you have a real-valued signal (i.e., an audio stream), you first convert it to a complex (quadrature) signal. You can do this in two ways. The first way is more obvious: use a float-to-complex block and feed the real part into the real input. Put a constant "0" into the imaginary input. The result will have both positive and negative frequencies in it -- plot it on a spectrogram! You can then filter out the negative frequencies with a complex bandpass filter. Or don't, if they don't bother you: you can always filter them out with a lowpass after mixing.
More simply, but less obviously, you can use a Hilbert filter to create a quadrature signal from a real one while eliminating (most of) the negative frequencies.
Once you have a complex signal, then you mix it with a complex sine wave at the center frequency of your signal of interest. Mixing is just multiplication, so use a multiply block with one input as your signal, and one input the complex sine wave (i.e., from a "Signal Source" block). Remember to mix with a negative frequency, as you're moving your signal down. No NE602 needed! You'll have your complex signal at baseband and can now filter, demodulate, or do whatever you want to it.
Nick