You can start by looking for pieces that resemble the characters' outfits in Pulp Fiction. For example, a black suit for Jules. Then, find a suitable head piece with the right hair and expression. You might also need to do some minor custom painting to get the details right, like the tie or the sunglasses.
His character could become more closed - off. Losing Peter, who was such an important part of his life, might make Yondu build higher walls around himself to avoid getting hurt again.