Are the bellows you mention square? I need bellows that are around 2.5x2.5 - 3x3 inches with reasonable extension (haven't figured out exactly how long yet).
As I have plans to use the outer, rectangular bellows myself, I might have a go at taking the body apart tomorrow. I will let you know what I find. I suspect that the internal dimensions are at least 2.25" square.
"People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.