Will the rear axle fit?

Plans are : do a burn out once a year maybe (yes I know burnouts look lame with a posi)

And 350 is a good price. How much do you think labor would cost if we put it in at the same time we changed the gears? ( might as well put it in with the gears, since the axle housing will already be open). What are the pros and cons of a posi vs a peg leg?