Sadly Dipstick I cannot get Loctite 518 here in Africa. But Three Bond is very good, not exactly the same ( its not anaerobic for example.)
The problem of British bikes is
(a) The vertical sealing of the crankcases vs horizontal of Japanese and most Italian
(b) Very narrow joining surfaces for some places, especially rocker boxes. Nobody complains that their magneto to crankcase joint leaks, because it is very wide!
(c) Abuse by previous owners. I have sometimes used Epoxy Steel to fill deep marks in joining surfaces, then filed down with fine hand files.
(d) Inadequate breathing of the engine- so much so that some recommend fitting a whole new breather from the rocker boxes, but this only takes care of upper pressurization, not lower.
(e) Impatience -- not allowing for time to cure of the various joints before oiling the engine and firing. As I said I apply enough Three Bond to "squeeze out" a half millimetre, maby 2-3 ft lbs torque( convert to metric, I can't)..then wait 12 hours, torque more.,. after 24 hours torque full and trim off the excess. I use anti-seize compound or moly grease to prevent seizure on first firing. Only after the engine has rested for a full cure of more than 48 hours do I add oil.
(f) No Flattening: every old bike needs to be surfaced, all components because after many years of life, the metal has cooled and heated at very different rates. for example 25 years ago someone went very fast in below zero weather, then his engine got splashed by cold water(!).....it is held together by the bolts and screws, but then "opens up" when you rebuild the engine. I use a glass plate 10mm minimum "float" glass, which is 100% flat by laws of physics + good German emery paper for all small surfaces, using the correct rub technique. For large surfaces, such as cylinder heads, rand crancases, the engineer is told to use proper shaving machines to totally flatten the surfaces, if any out of flat is detected. For this a "float" glass thick plate in very necessary
However do not flatten Triumph Cylinder heads this way. They need a straightening machine instead.