Spectrum Inversion Problem
I don't think that FM has anything to do with this, unless you are using the term "spectrum inversion" in an unusual context.

The original signal is presumably a real signal centered at 1200 MHz with a bandwidth of 100 MHz.  If you sketch its spectrum conceptually, it will have some content from 1150 to 1250 MHz, and a conjugate-symmetric version of the same thing from -1150 to -1250 MHz.  The conjugate symmetry follows from properties of the Fourier Transform and the fact that the original signal is real.  Call the portion of the spectrum at positive frequencies the positive image, and the portion of the spectrum at negative frequencies the negative image.  If your sampling ends up reversing the positions of the positive and negative images, or if you convert the negative image to complex baseband, then that's spectral inversion.

To find out whether your a sampling scheme causes spectral inversion, recall that the spectrum of the sampled signal repeats at intervals of the sampling rate.  Sketch this operation for the proposed sample rates and look at the position of the positive and negative images in the region from $-f_2/2$ to $+f_s/2$.  Does the spectrum have the original sense, or has it been inverted?