I developed film from exactly the same era and, likewise, only had D76. Storage conditions will be the decider. My roll came from a second hand camera place housed in an old packing shed - insulation non-existent. Who knows how many scorching Australian Summers it went through or miserable winters there.
At any rate, all the film I was given from that shop was developed in D76 1:1 for 10 minutes.
The backing paper and the frame with the least recognisable people (It was someone's birthday party - I feel a bit sad that I have these! If you or anyone you know celebrated their birthday in the Tarra Valley National Park in Australia in the 1970s, your photos are ready to be picked up!

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