No, no major machining, but there will be a few issues. You might want to check to see what years of oil pump will bolt on the new cases without modification. Worst case a hole may need to be drilled or plugged.
Your cam will not fit a normal generator cam cover, and your pinion gear would also need to be changed to the longer pre '77 version for a circuit breaker drive gear to mate to (and don't forget you will also need an idler gear if you plan to use a generator. Your nose cone ignition also will not work unless you were to run an S&S distributor with the reverse rotation drive gear.
Top end should be a bolt on. You would want to check the pinion bearing fitment to the new case race. S& S cases usually come with a new Timken for the sprocket shaft, so you will want to remove the Timken half that is pressed on your old flywheel.