Going by those heights, a good visual comparison might be found with Bow Valley Square 2 and 3 (in Calgary; height difference is comparable, 116m vs 143m)
This should help visualize what we may expect from 300 Main vs 360 Main
This picture is actually Bow Valley 2 (116m, 381 ft) vs Bow Valley 4 (134m, 440ft)
Here is Bow valley 3, the tallest one to the Right (it is 143 m, or about 469ft)
Bow Valley 2, 116m is to the left
And here is Bow Valley 3 (again on the right, the tallest of the 4 towers) with Bow Valley 2 (in the background on the left) -> This should be apps the difference between 360 main (~ Bow Valley 2) and 300 main (~Bow valley 3)
Thought this might be a good visual comparison, based on the heights that could be expected, for those who wish to have an idea of what that 70 foot difference might look like
As others have said, noticeably taller. Will stand out in a good way.