You have a very high chance to get BBA through PMSSS after passing the 12th board exams with 78.6 % if you have a category.
Last year a student who belonged to Scheduled Caste (SC) category got a BBA college with around 57% in the 12th class.
A student with 80% and open merit struggled to get a BBA seat in the 3 rounds of PMSSS allotment.
Though with 78% and open merit there are 50-50 chances it depends on the no. of application who want BBA through pmsss