I have an all matching first run Luger 9mm one of this first imperial arms order. It is all matching and in immaculate shape, the debate among friends is that you can us modern 9mm my opinion is i should load some light loads to accompadate new pwder and the higher pressure it creates. So the question is to shoot modern ammo , do not shoot, or make light loads using modern powder. Thought I do not want to mess up a pice of history that is over 100 years old.

Myself, I would not shoot it.  There are plenty of other pistols to shoot.

Now, I understand the urge to shoot it.  I haven't always been successful in fighting that urge myself.

Modern ammunition should be just fine.

You could load lighter, but then it might not function.

Modern powders might enable higher velocities at standard pressures, which might cause concerns, since this is a recoil operated mechanism.  But, you don't have to load to higher velocities.  Standard velocities should work just fine, and if pressures are lower so much the better.

Plenty of old school powders around if you don't like modern powders.  In the US, bullseye and unique come to mind.  Both still popular, even after a century of use.

I would give it an honorable retirement, and shoot some thing else.