I want to say into his early 80s.  I recall seeing one of their
documentaries where he was using a modified regulator system for him:
they took an AL80 type of tank and had mounted probably a 1st stage to
the yoke, but this 1st stage was probably modified in that the orifice
in the HP port had been drilled out, as they used an HP port to route
a hose from the tank around his body to his chest.  On his chest, they
mounted a classic old single stage regulator ... this put it very
close to his diaphram and could be tuned up as desired ... and he then
presumably breathed the doublehose relatively normally.

I can't recall the date of the film, but Jacque was in old fashioned
black wetsuit and everyone else was in the fancy silver stuff, so it
was of the more recent vintage.  Hope this helps to narrow it down.

-hh