Stock floor b/d

I've been studying IF customs stock floor drops. I haven't started workin on my truck yet but I think it's a waste to shave the top of the frame and modify everything.

I was thinking for mine to just shave a few inches off the bottom of the stock frame until it's level with the body and just move everything above the frame. I don't know if it'd be safe but it seems like it would work to me. what does everyone think