Yes, this would work. On an 18" robot it’s likely you could reach to 60" with an 8 bar.
There are two disadvantages with these kinds of mechanisms this season. One is that they don’t lift in a straight line, which makes it more complex to line your robot up with objectives at different heights. The other is that they don’t lift in a straight line, so your centre of gravity will shift forwards as you lift the arm. Since cubes are heavy and your arm will be long this could easily lead to you tipping over every time you try to lift more than a couple of cubes.
Yes, it might be able to reach 60" if designed well, but there is still the big problem of robots tipping over due to a shift in center of gravity. The robot would only be able to pick up a few cubes at once without toppling over. If using that many bars, you might as well go for a scissor lift instead, and be able to have linear upward and downward motion.
Toppling over this year is also going to be a huge issue that teams are going to want to prevent entirely, otherwise they run the risk of severely damaging the robot, the field, or maybe even other people (if the robot falls outside of the field perimeter) which it’s likely to do at heights as high as 5 feet.