Welcome aboard, glad you found us, we will be happy to help as best we can.
Assuming you know a UO8 is the entry level model with lots of fans, classic bike boom first bike for many.
It will be somewhat of a challenge no matter what, being as you are new to this, the french thing can be tough on even the hardiest of souls.
If the spindle is bad, the cups may be as well and they can be one of the most challenging thing on bikes to get out if they are rusted in place. Key in my mind is to bring the "A" game at the beginning, assume it is stuck and prepare for that from the get go as any damage from failed attempts will make the task much harder.
On top of that mixing and matching these parts usually requires a selection of parts to work with. The best way to start this is to find a bike co-op or kitchen near you and volunteer there for help.
I have a foolproof method for this that never failed me or anyone that I know of, like I said it requires good tools and some skill to wield them.
Oh, and go around, say "Hi" and of comment on other posts to get to 10 and then, "pics or it didn't happen", we need em to help and they are a must, good ones and plenty of them.
Good tools are a must for this and the older french stuff can be