Option A: Set chart's height to read the normal height signal (so height of the view box it's in) and then just make your visualization in dashboard super tall.
Option B: Pending your version, you can set each one of your chart items to a set height and set signal height (for overall viewbox) to 100 * each item's height. Again, this creates runoff but in the later versions of Kibana, when you put that in the dashboard, you will have a scrollbar for your users.
Option C: If you can categorize your results, then you could make a series of visualizations, one for each category. This way you abide by standard visualization practices of not overwhelming your user, giving them access to all of the data, and respecting how human brains are wired to see mass amounts of data broken down by category and/or type (ideally no more than 10 per visualization). For example, let's say you had economic data with box plots of distribution of countries by various metrics (i.e. GDP, Budget Balance, etc.). Well, GDP has about 10 ways of looking at it (change, year on year, month on month, quarter on quarter, value, services, goods, non-oil, etc.) that could be in ONE visualization. Then the various Budget Balance ones in another visualization, etc. Makes it digestable, easy to understand, and easy to snapshot to a report.
Hope that helps!