Sell it and buy one with a v-8 if that's feasible to you. It's always cheaper that way, and people are looking to get rid of v-8 cars now any way. Unless it's just a project. Then pull the engine and swap it.
there are supercharger complete kits and exhaust systems that will give you more than enough power.you wont have any problem running with the v8s and you get way better gas mileage than you wouls with a modified 4.6 v8.check out vortech and good luck