To swap in an 8 and 3/4 or not ?

Hey fellas, In my 69 barracuda I currently have an 8 and 1/4 bbp rear end
with 321 open gears in it. I am just building a nice driver. Anyways I would like to have a suregrip in it. Do you think i would be money ahead to just put a suregrip in my current setup ? or find an 8 and 3/4 rear end ? If I do that I have to shorten driveline, get bbp axles etc correct?
Little confused on this