Plumbing pitch puzzle

I'm trying to revive an old airless paint sprayer (Wagner W500) and
made decent progress until I met the fitting on the paint reservoir.

The male thread OD appears to be close to 0.850" with a pitch of 0.125
though it's a German product so likely not made to Imperial measurements.
The male fitting ends in something resembling a slender male flare. But,
the threads are too coarse for any flare I've ever seen.

The reservoir is plastic molded around a female brass insert. The plastic
has cracked radially, allowing paint to leak around the periphery of the
brass insert. There's no easy way to seal the cracks and they'll likely
keep growing anyway. A new reservoir is hard to find and expensive,
$100-$200 depending on where I look, with lots of "out of stock" notes.
There don't seem to be any aftermarket suction hose kits, as this pump
is top-inlet and the modern types are all bottom-inlet.

Does anybody recognize those dimensions as any standard fitting type?
I _think_ the path of least resistance will be to fabricate a suction
pickup hose. If there do exist "standard" fittings of this type that
seems the place to start. If the threads are orphans I could try to
fabricate something cobbled up using the brass insert as a foundation.

Thanks for reading, I think mentioning "brass" makes this an on-topic
post 8-)

bob prohaska