From what I read in the service manual, all swept measurement are with RF in and measurement out at the same frequency. That's work that should be easy to do with a VNA as there is no frequency translation. Issue is perhaps the loading of the circuit. The VNA is 50 Ohm input. You can put a series resistor in series with the VNA input to increase the impedance. It depends on the circuit output impedance what is acceptable. Perhaps even add AC decoupling if needed. 1K series resistance attenuates the measured signal by 26.4dB but the passband shape should still be clearly visible.
All IF measurement seem to be done maximizing the S-meter reading. One measurement needs a frequency counter. That can be done with the scope as it's a digital one.
Although the VNA will generate a square wave, for this radio it should not matter.
I also saw an absolute measurement with at 100 dB input to adjust the S-meter. That's a huge level, depending what the unit is :-).
