just fitted s50 cams to my 328 also single vanos by my mechanic and not myself.
You'll need to lock up crank/flywheel.
Line up the 2 square plates at the back of cams
vanos will take car of timing if fitted correctly.
There should be cam gears/spindles on the cams one on each when you refit the vanos both will need to lock into place as both are splined.If i remember right it was a 1/4 turn clockwise then anti clockwise.
2 hand turns of the crank and if your square plates are still lined up job done.
when my cams arrived only had 1 spindle, fitted fine but when we turned crank by hand the inlet cam was retarded as a result.
Double check before you fit.