Here is my ITZ robot which was a cross between a dr4b and a 6-bar.
My tips for you are that you need to keep everything consistent, both sides need to be cross-braced or connected together in some way or form. This year if you are expecting to lift more than a few cubes you will need 2 100RPM motors and probably a 1:7 ratio. I would personally power the lift from the middle section much like the ITZ robot I linked you instead of powering it at the bottom like the other video.
If you have high strength shafts I would use them especially this year because of the weight being carried by the lifts, just be sure not to rely on them and instead rely on x-bracing.