Welcome to forum, there seemed to be more 400s represented here than any other model. Not sure if that's still true.
Also as Ash, been to Zagreb once on the way to Greece, but on Z650 a few years later in 1980 The road between Zagreb and Belgrade was a nightmare I remember with trucks hurtling towards you on the wrong side of the road as they crept past traffic on their side.
When we arrived at Dover for the trip, there were group of bikers behind us. Where are you going they said. Greece through Yugoslavia we said. Oh we went last year and our mate got killed.