I won't bugger it I promise!
just remember a few things:
-remove the movement by lifting opposite side from the crown/pushers, and insert same way
-use a bit of polywatch on the caseback threading to improve it, it's usually gritty ootb. and it can twist the movement/dial when screwing, or mess the gasket
-cut the stem carefully by steps if needed. Too short the stem will not engage as the crown will thread, too long it will move the dial sideways when you screw the crown
-you can remove the bezel insert with a thin slim razor blade or the thinnest guitar pick (better). You will need this to align the bezel 60 on the dial 12