@CraigK that board should be great for you, they are unfortunately not that widely available. You will just need to think a little about where the power for the motors comes from, as discussed earlier in this thread.
Which version of the microscope are you planning to build? Please note that there are a couple of known bugs in the current V7.0.0-Beta1, as in the thread Openflexure Microscope V7.0.0-beta1 released