in too deep: trying to go BBP on a 68 barracuda and its going.. poorly.
i highly doubt someone custom ordered axles just to fit a center section in that thing. pull an axle and see exactly what you have.
if it were me i wouldn't waste the time re-drilling small bolt axles.. grab a set of dr. diff axles and then big bolt drum brakes. i have 11X2" drums on the back of our dart. they have worked very well for many years..