I have collaborated some of the information for dates and links for admissions to old IITS. This can be integrated with important dates (https://gatecse.in/important-dates/) that is present in GO(used the same column format). Maybe Some of the admins can integrate the same.
https://docs.google.com/spreadsheets/d/1jM16zPHaW2yMF7cafYAe4oZjD2mCQq47vDVO2sv9kQo/edit#gid=0
Also turned the link for editing. Maybe others can also contribute.