Castrol A747 was one of the best racing 2T oils in the days where fully synthetic high performance 2T oils were in an earlier stage of development.
Castor oil is a superb boundary lubricant, even by modern standards, but 747 is only for premix, it is too viscous for an injector.
However, the latest fully synthetic 2T race oils offer equally good lubrication properties, and don't pose a possible risk of 'gumming up' (note 'possible').
Castrol had to develop a modern version of 747, called XR-77 (fully synthetic) because 747 didn't mix as well with Unleaded as it did with AVGAS.
This too is also premix only.

For an NSR wih an oil injector, stick with Castrol TTS, or equivalent injector oils from Rock Oil, Silkolene, Motul (and others), all of which are very good.
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30