FIR compiler II parameter settings for sample rates below 1Mhz

On the issue of cutoff point. If your signal extends from 0 to 33KHz and there is no unwanted power outside 33KHz then aliasing will not occur if your cutoff is 520 - 33 = 487KHz

The filter works at 1300Khz so your cutoff ratio becomes 487/1300. your passband will be 33Khz and transition band from 33 to 487

If you cutoff at 33KHz sharp then that requires a ratio of 33/1300 and makes a big difference. The Nyquist will be 650Khz at output so 487 will stop any aliasing.