Just curious. Can I use one HP7475A HP-IB with one Oscilloscope which
claims compatibility with the HP7470 (GP-IB) ?
My guess is 'yes', and it won;t do any harm to try it.
HPIB and GPIB are the same inteface, at least at the hardware level. So
you won't damage anything by plugging it in.
Both of those plotters use the HPGL comamnd set. It's possible
that your 'scope uses a command presnet in the 7470 and not the 7475, but
I think it's unlikely.
-tony