I would stay away unless the price was "exceptional".
Yes, Merc did own Force but here's the story.
In the mid 1980's when Chrysler was circling the toilet, Bayliner boats bought out their outboard division - machines, patents, parts - the whole shebang and gave it to their own U.S. Marine division.
Their plan was to build their own motors to package with their boats and keep the price point low. They first called the motors Force by Chrysler and after a year or two dropped the Chrysler part. However, the motors were built pretty much to pure Chrysler specs.
In 1986, Brunswick (a giant in the marine industry) bought out Bayliner, getting the U.S. Marine division as part of the deal. Since Brunswick already owned Merc they had no desire to keep two separate outboard companies and basically rolled Force into the Merc line.
At the time Merc was already having Yamaha produce a "budget line" of motors for them which were being sold under the Mariner brand. These Yami/Mariners were 100% Yamaha, but were generally older technology that Yami had either stopped producing themself or did not contain the bells/whistles of the models with Yamaha decals on them.
Force became the "sub-budget" line at Merc. There was thousands of Chrysler parts still in inventory and likewise, Merc had thousands of parts they were no longer using on "their" own models which are almost always at the "leading edge".
So "Mercs" Force line gave them the golden opportunity to get rid of everything sitting around with dust on it.
That 40 Force which was built in 1996 has Tillotson carbs on it which Merc stopped using in the late 1970's (and parts are getting very very scarce - most "kits" do not contain everything you need because the supplies are simply no longer there, so every couple years the kits get smaller). And while this particular model did not have the Prestolite (Chrysler) ignition (which actually would have been an advantage since you can still get parts for them), it used an early Merc CDM ignition for which the CDM module and the trigger is long discontinued and no longer available.
Anything the Merc was no longer using on their own motors got cobbled into the Force models.
There was a reason that a 40 Force sold for about 60% of the cost of a 40 Merc and about 80% the cost of a 40 Mariner. Most were built as "disposable" motors.
Now that is not true of every model, some still have decent parts support - the 40 Force which was a Chrysler/Merc hybrid (for it's entire model run) was just not one of those models.
If it runs now and it was taken care of, it may last a number of years - but if something goes "flooey" you have nothing more than a couple hundred pounds of scrap aluminum.
So don't kid yourself - they were "produced" by Merc, but they bear no resemblence and are no longer supported.