Pre-oiling a fresh 1275 rebuild

Hi All, the old 1275 is good as new again.  Sleeved her back to
std.bore.  Turned the crank to 10/10 way back in 1978 and it showed no
wear beyond that even 26 years later.  Anyway, I'm looking for
suggestions how to fill the oil passages before cranking her up the
first time.  What do you think of  Castrol GTX 20/50 for the initial
fill up??  Anyone willing to help???  Many thanks,

Jack