If it's really really clean and has new rubber, it could be worth $140. UO8's (though heavy and reviled by some ) offer a nice sedate ride and are very classic, very aesthetically pleasing bikes .
French foibles and threading is only a problem if you want to put Japanese part on it - (but then again I ran into the same issue trying to put French parts on my Japanese bikes )
UO8's have heavy steel wheels which you should replace with alloy wheels -this will help braking and reduce weight where it's most beneficial. - So there is additional cost in it for you.
You will have to have the bb bearings serviced if they were not done recently. . . The cottered crank service can be a challenge for inexperienced home mechanics.
The ad mentions "best" offers - if you like the bike, go there in person to check it out and if there are no issues, offer some amount of cold cash. You can always add more if the seller is steadfast, but very often they will accept an offer in person.
Something is worth what someone will pay for it. My own experience is that there are some people who make $140 a day, some people who have $140 left over as disposable income at the end of the month, and some people who can simply add $140 to the bill of the next guy who comes through the door by adding one billable hour to the account.
Toronto is a fairly healthy bike market and this looks like a comparable bike to the one you were asking about..
If this bike sells or does not sell you will have your answer.