When it comes to used engines, if you need one, you should have no problems finding one. They were common on the Ranger (89% of them had the 3.0L, according to autozone) and worst case you can take one from a Taurus, Sable, or Windstar and by swapping manifolds and a few accessories/components and headgaskets. Definitely more work, but the base engines are out there by the millions.
If you do go the used route, though, I’d replace the timing chain cover gasket while the engine was out - that’s VERY easy to do then, and considerably more difficult later, and these engines did tend to leak coolant a bit at that gasket. That was actually one of their biggest reliability faults, and it wasn’t even that big of a problem if you watched your coolant level (rates of loss were generally very very low). Unfortunately, the weak spot on the gasket was on the upper coolant passageway, and when it leaked, it leaked at a point right next to the headgasket. I know some people who were told their engines needed a new headgasket by an unscrupulous mechanic who pointed out that bit of coolant puddled in a depression by the headgasket… when they looked up headgasket and taurus/windstar online, they saw tons of hits and bought the mechanic’s line, without realizing it was the 3.8L, not the 3.0L that had the big headgasket issues… but when I told them to get a compression test done, what do you know - the engine passed with flying colors. That $1600 headgasket bill suddenly dropped to a $450 timing cover gasket replacement.