Why do you think the run chase stat is relevant?
The reason it's rare is because of so many more factors than "Can you score 350 in the 4th innings?".
The biggest one is time. How often does a side get 170 overs for their 4th innings? Almost never.
Then there's the question of "How often has 350 been set?". Most teams would give themselves a much bigger cushion to go for a win.
The important questions is can 350 get scored in the 4th innings, and the answer to that is a resounding yes in every case of the 30 or so where 350 was scored, regardless of whether it was enough to get the win.
By the way another thing that's relevent is that there's loads of 4th innings where teams could have gotten 350 but won before they got there, like England last week, where they were 300 odd for 3 in the 4th innings. They could easily have gotten 350.
The chase statistics are niche at best, not really that helpful.
Winviz now has the teams almost level.