The sad fact is that everything takes longer than what you think it will.
If you have mechanical ability I believe you can have all of the connections marked, the old engine harness removed and the old engine disconnected and out in a day, working at it that is.
Then you may or may not want to clean up the engine bay both from grease and oil and also from the electrical nightmare that will pursue removing the old harness/computer and getting the new one ready to install, well maybe not a nightmare but a little confusion, then maybe some paint, so again, working at it there is another day gone.
Next you will need to mod/replace the Motor Mounts on the frame, removing the old installing the new and general setup, another half a day or more. Don't forget the heater box mod, I did mine with a really hot heat gun but the box will either need to be cut and patched up of melted and formed back enough to fit the passenger side head/cover to fit, so maybe that will be another day or so.
As you can see things start to add on time at every turn.
Then you can start the engine install, I hope you will have help. a couple of friends will work, engine alignment and trans mount setup (my setup used the original 2.9 Manual Trans mounts) make sure all is square to the frame.
Once all of the mechanical parts are installed and secured you need to start the electrical, this can take hours to days depending on the condition of the replacement engine harness and your abilities. (The fuel pump was the only real problem that my swap had electrically).
I had three friends, all with mechanical abilities and one friend and my self with electrical knowledge and the whole swap, took about a week to get the truck back on her feet. We are talking about 50+ hours for three people that had a little knowledge of what was happening and one of the guys had done a similar swap before.
If it was me in your shoes, plan a week with two weekends and that is working at it as much as possible and don't get discouraged if things don't go as planned because they won't, you can plan on that.
Take your time and do it right, this will turn out to be a great swap and the truck like never before.
This engine should have been offered in the Ranger from it's inception, my '88 Ranger 4WD/5.0L Package just felt good to drive.
Luck on the swap.
p.s. Don't take everything I say literally, everything take times, depending on your abilities and your wanting it done, things will go wrong and you will need to adjust, ltr.