A 555 would be OK as a "proof of concept", to see that the idea of injecting 150kHz into one of the crystal connections will bring the radio back to life.
But as far as I could tell, the 150kHz crystal is used as the reference for the synthesiser which determines the frequency that the radio is listening to, and so the frequency needs to be accurate and stable.
With the best components in the timing circuit, a 555 comes nowhere near to a cheap crystal when it comes to frequency accuracy and stability.
JimB