Can I add a center-frequency parameter for my noise generator flowgraph, is there a different noise source that has this parameter other than the generic noise source block?
The noise from that block doesn't have a center frequency because it's "white" — it has an equal power at any frequency (up to the half the sample rate, anyway, and you can extend that as far as you need). You can give it a shape by filtering it. Whatever the shape of the filter is, will be the shape of the resulting noise power. If you run it through a bandpass filter with a given center frequency, then the noise will have that center frequency.