Looks amazing! I'm excited to follow and see the rest of the costume come together. I'm glad you're bulking out your frame and extending your arms and legs--I think the biggest failure with most Big Daddy cosplayers is "bobblehead syndrome", and it sounds like you've nipped it in the bud.
Do you mind if I ask how you achieved your finish? What were your texturing/painting techniques? I've been wanting to re-paint an old Pyramid Head, and I think the sort of pebbly sand-cast texture you've got here is exactly what I'd be aiming for (I'd just finish it as rusty iron instead of tarnished brass). Either way, your paint job is gorgeous