Yes, it is Spanish
The date of proof code is R1 = 1973
1350 gms is the barrel weight
I can't see the proof - likely 1000 kg/cm2 for a service load of about 10,500 psi
It was by Industrias Marixa Armas (IMA).
https://www.gunsinternational.com/gu...n_id=100427073
It would help future posters confused about their 'Parker' to direct them here
https://www.shotgunworld.com/forums/shotgun-id-value.5/