Miran, I have no knowledge of your car, though I can understand the reason for your confusion.
My 1986 Morgan +8 also has a manual gearbox, and ATF is specified for it too.. I would go with your manual`s specification if you can find that oil, or an equivalent locally.
You might find some information on GoMoG..
https://www.gomog.com/allmorgan/gearindex.htm
