George

Yes, I have an original Brno ZKK brochure c1967 which shows all three models with integral rear pop-up peep sights, and forward banded sling swivel.

Original factory calibres were listed as follows:
ZKK600
.30-06
.270 Win
7x57mm
7x64mm
8x57S
8x64S
9,3x62mm
10,75x68S

ZKK601
.222 Rem
.222 Rem Mag
.243 Win
.308 Win

ZKK602
.358 Norma Mag
.375 H&H Mag
.458 Mag

As you say, ZKK600's were officially imported to Australia in .270Win, 7x57mm and .30-06... though I believe other calibres were available on special order. I've seen one in 7x64mm for example.