First I should clarify the "unconditionally stable". If the circuit is built using standard RF practices it is stable but because it is so sensitive it will pick up strays if not grounded and shielded. I did not have any 220k resistors on hand so I used 2 100k. I left all the leads full length and the leads made antennas causing cross feed. So I reworked the bias with the leads clipped short.
I connected the output to my AF amp and powered it up. I could hear some static. Touching the input I hear my local station.
I will do more test later but it appears to work as designed.
EDIT: I used 200nfd caps in my build.