Advice on rear swap

Any idea how big the center register is on a 8 1/4? I can measure my Cragars and see how much space I have for it. Leaning towards option 1 if All i have to do is take the drums and axles to a machine shop to drill for the SBP. Seems it would be cheaper than to have the E Body 8 3/4 cut to size. I don't have much extra cash for this but want to jump on the deal before they are sold.