I bought an OSR2 and want to know how to upgrade it to SR6 later on

Hi, I bought an OSR2+ with a twist and it’s going to be here in a week or two. How hard would it be to upgrade it into an SR6 with a twist since I’ve recently learned the SR6 is superior in multiple ways? What parts and servos would I need and would it be easier to have the 3D printed locally?

Update: I decided to ask my merchant and he updated my order. Am going for the best option.