Just a point but dwarf burms and even 50% dwarves are known to be more defensive/twitchy than their larger counterparts, and they're still a large snake. So if you're looking for a pet they may not be the best choice due to temperament.
I would look at Dumerils boas or olive/Papuan pythons if you want something that will get larger than your boa imperator but will be better suited as a pet.