The facts known about this engine is that it came to Sweden for over 30 years ago from an american dealer of used motorcycles and parts. I have done some research and have with help from the well known Triumph expert Claudio Sintich got this info.
T100SC H36489 was built on 25th September 1964 and dispatched to Johnson Motors, Pasadena, USA on 27th September 1964.
This is a 1965 model year machine and in a large batch of T100SC bikes for America. There are no special interest notes in the factory record for this bike separately now. This probably means that your engine was prepared for racing by Johnson motors and used for dirttrack.
This engine looks more "works" than Triumphs own works engines. It has welded inlets and also a welded reinforcement around the gearbox. It has some kind of surface treatment that are almost black. The double breathers are rarely seen. The engine is missing some minor parts but will need an major overhaul.