I think with Kaz there are a lot of unknowns. He log pressed before the technique was worked out so he ended up basically one motioning everything. That shows his strength, but it's hard to know what he would have done with more of a push press technique.
For stones, Kaz was retired before the stones really took their final form. He did do the 'basque' stones at WSM in the late 80's, but he didn't really do very well. However, he was a walking pile of injuries by that point, so it's hard to say how he would have done with stones in his prime.
Girls squats and money deadlifts were more popular than frame deadlifts in Kaz's day, but I don't doubt he would have absolutely rocked a car deadlift.
I would take Magnus ver Magnusson for his dominance in a more mature strongman environment. Mariusz got most of his victories during the schism when many of the best strongmen weren't in WSM. If they were options I would take Big Z or Brian Shaw over any of these competitors, given the chosen events.