Tell you what... just go out and find the BIGGEST supercharger you can possibly get. One of them oldskool roots blowers or perhaps go steal one off a forcefed dragster. Then when you get home, rip your intake manold off and toss it aside. Next, somehow find a way to bolt that gigantic blower on your motor. Granted, it may be larger than your little SOHC engine and the install may look like total crap but at least you'll have something enormous to look at while cruising the streets and oh yeah... set the boost WIDE OPEN. Whatever your mechanic says is the limit...5x it!
Wait a sec... did you say you wanted 350hp relatively safe with just a supercharger? I dunno I'm sure you'll need a good tune, and maybe a new fuel pump, injectors, etc. Let's wait and see what others have to say that's been this route.