With all you've done and figured out already this a piece of cake.
All I did was look at it, walk it through in my head, go for it.
Method worked having jack coming at it from front of truck, from side jack wanted to roll out when you loaded up spring tension.
The stem is started into top hat when spring starts loading up, bottom bolt in place, the assembly is captured by lower mount and top hat where it gona go, no where.
You control speed of things loading up with jack, check alignment of things as you load up spring. I left top hat nuts hand tight till things were in place torqued em all same time.
Go old school, rely on the gray matter between your ears, started wrenching before the Net was invented, way I look at it.