300fwhp will be possible with alot of money involved, anything is possible.
but if u want alot of HP made..look at turbocharging rather than superchargers.
+50whp is made froma supercharged kit by jackson or vortech.

which is better s/c?
well JR will have instant response
will have a little lag... not as much as turbo but some lag due to its centirfugal design rather than root style.