What would a graph of magnitude >7.5 earthquakes over last 400 years compared to Grand Solar Minimums look like?
As others have pointed already in the comments, there is no earthquake data extending that far back. But we do have data for the last century. In a similar way to my answer to this question. Here I've plotted the yearly count of all of the earthquakes worldwide from 1900 to 2018 of magnitude greater of 7,7.5, 8, or 8.5 found in the USGS Earthquake Catalog that span back to year 1900 (bars), along with the total number of sunspots per year from the Sunspot Index and Long-term Solar Observations (red line).  Here is the resultant graph:



As you can see, there is not any significant correlation between frequencies of large earthquakes of any size and the solar activity. The solar record shows the well-proven 11 year solar cycle (actually it's a 22 year cycle with two similar halves). On the other hand, the earthquakes show no clear pattern.

Unfortunately, for the grand minimums like Maunder and Dalton's solar minimums we do not have a reliable earthquake record. Nevertheless, given that EVERYTHING we know about physics and earthquakes suggest that there is NO mechanism by which solar activity could possibly influence earthquakes. And provided that there is no evidence of such correlation in the 100+ years of the instrumental record. There is absolutely no reason to believe that such correlation exist. The answer to this question should be informative too.