What I do to make tops look good with large breasts are to edit genesis to smoothing modifier and leave it set to regular. The smoothing helps with bends too.
When auto fitting only choose V4 but don't pick what type it is.
For the top, that gets edited to smoothing modifier as well. Depending on the clothes it's base or generic and set smoothing to 100 or more.
Last, the cleavage modifier from Daz helps a lot.
3-D Age's stuff works we'll with the above as well as most others should too.