Try blue loctite 243 threadlock. Seals (does not dissolve in petrol or oil) and keeps parts well together, but made to be able to unscrew with moderate force when needed. Clean well, then let it harden for an hour at least.
Good for avoiding most sorts of overtightening (to get rid of leaks, or avoiding destroying threads). Nothing will unscrew itself again, and no problem in getting stuff apart when one wants to.
Getting the taps facing the right way is indeed a difficult task and keeping them from leaking and not so they start revolving with vibration!
Have used 243 together with suitably thick fibrewashers to get the taps pointing in the right direction without stressing the washers, and then it all stay in place, sealed and secure.
Remember loctite's are no fillers, they harden only in near-airtight spaces, needs good contact beween surfaces or threads to do their job.
But all this is of no help to me when the petroltaps themselves are leaking ! I also liked the vintage looking models, but have given up, will order the others.