If you need to do an alignment on an FM radio you need an RF signal generator not a VNA. In my case I used the TinySA to generate the IF frequency, probably 10.7 MHz in your case, and the RF frequencies. It also needs to be able to generate an FM signal as well as un modulated carrier. I just did the AM and FM alignment on a 1960's transistor radio and the TinySA was perfect for the task. I wouldn't worry to much about the impedance miss match for doing an alignment. Once you are past the 1st RF amplifier it won't make any difference.
Terry W7AMI