the only rootstock that i have heard that causes dwarfing in mangos is cashew they are close enough related to graft but have never heard of the longevity of that graft. most of the other dwarf varietys are just grafted onto whatever seedlings they have available at the time they do there grafting. so in mangos anyways it seems dwarf or not is in the scion wood itself not in the rootstock. it may be slightly possible if you can find someone with the varietys that are dwarf or semi dwarf you could get seeds from them and try those as a dwarfing rootstock but dwarfs donot not always produce dwarf seedlings so not sure how well it would work. i donot grow mangos i am allergic to them but several of the members of the rare fruit council i am friends with do allot of mango grafting and i have never heard of any variety that produces seedlings that will dwarf a mango. some varietys just refuse to be kept small its optimal for most any fruit tree to keep it around 10 foot tall no sense in a 50 foot mango tree but its mostly done with pruning, some varietys are just more cooperative than others