Having recently identified a 3rd cousins birth father and having reread your original post I would say don't rule out the married man who is too old (!who gave the description+ under what circumstances ? )
Possibly add a.hypothetical much younger half brother to your maternal uncle give him surname ,"DNA connection ' + have him as father to your top match . Living people won't show on trees but thru lines will show up to you and it will be easier to assess connection
Half first cousin is more likely with those numbers
( My.mother has a half first cousin who is 20 years younger than his half siblings from a second marriage)
I would also suggest grouping your matches by location .
Can you match other relatives to Tasmania or other significant places
Good luck it's a slow process but as more matches come in you may get nearer the answer
Take this advice.
Do keep all the options open, on the back burner yes, but do not discount anything.
Build separate trees, even multiple trees based around the same person.
I did just this with a 110cM match and found that they were a third Cousin, the person had no tree but had at least used their birth name as their user name and as there were well over 100 possibilities as to who they actually were it turned into a long slog.
Where you have pedigree collapse as seems to be the case in your text you cannot rely on sites like DNA Painter to give accurate probabilities.
An odd ball suggestion to work your problem, create a Presentation, this is what I have just done, it is about solving problems, all 69 slides, off the wall thinking, and techniques learned from members of this great forum.
Work the problem as one of my bosses used to say, just why he never worked his own problems remains a mystery.
