As the title says, preferably with the latest possible PoD and an emphasis on turning the crippled economy around.
I would postulate Grand Duke Cosimo III having the top-tier scientific education that his father, Fernando II, suggested. This would swap the theological education that his mother, Vittoria della Rovere, forced on him, leading to his calamitous reign.
Cosimo continues his father's vigour for the sciences, bolstering the Accademia his father built, attracting some of Europe's finest scientific minds. Instead of enacting unpopular and constricting laws, he instead amends the taxation and reforms the economy of the state. This different Cosimo marries someone other than Marguerite Louise, having sons that could continue the dynasty into the future.
I would postulate Grand Duke Cosimo III having the top-tier scientific education that his father, Fernando II, suggested. This would swap the theological education that his mother, Vittoria della Rovere, forced on him, leading to his calamitous reign.
Cosimo continues his father's vigour for the sciences, bolstering the Accademia his father built, attracting some of Europe's finest scientific minds. Instead of enacting unpopular and constricting laws, he instead amends the taxation and reforms the economy of the state. This different Cosimo marries someone other than Marguerite Louise, having sons that could continue the dynasty into the future.