You are looking at probably a $5000-$6000 job.
I would start by yanking the engine, tearing it down, and rebuilding it with forged internals. This will probably cost a couple grand depending on how good of a job you want to do (arp stuff, upgraded timing chain/gears, etc...). Of course your exhaust needs opened up (headers + custom exhaust = $500), and you need an injector upgrade of at least 24#/hr and 255lph in tank fuel pump = $350ish?
I would probably buy a Holley Systemax II head/intake + cam package as well (not sure if you can specify compression ratio).....cause it would pain me to put stock heads/cam back in when you are this far down. But, you don't have to.
Then I would probably piece together some form of a Vortech S-Trim kit. You can probably dig up the parts for $1500 on Ebay + $500 in custom parts (discharge tube plus any clearance issues with brackets, etc...). And hood clearance will most likely be an issue. So you can either upgrade hoods ($500 easy) or do more fabrication to get everything to clear.
It's a big deal, and you need to know how to yank the engine, rebuild it, and fabricate stuff. Plus the tools required. I'm not sure how much it would cost to forge a 5.0L, but I would start by hanging out on
www.corral.net, surfing their classified ads for parts, and buying a MM&FF for $6 cause they have like 200 pages of parts vendors.
IF all you want is to buy a supercharger kit...........you will most likely NOT find a used one, which means you pay $3500+ for a kit to fit your application. And if you have mileage on the motor (I'm guessing 100K?) then you can't pulley it for much boost without sacrificing the durability of the motor. A centrifugal blower vs. a Kenny Bell, Magnacharger, or other roots blower will probably be friendlier to long engine life as long as you aren't revving to 7000 rpm all the time. But any blower that will add significant power will just put a timer on your engine until it starts goes to crap. If you run the blower easy enough to not hurt the engine, then it's not worth your trouble. You can get performance like that from gears, shift kit and other bolt ons. If you actually push the blower then the engine won't last long unless you build it for that application.
And don't forget that your AOD trans probably won't appreciate the much higher torque. So look for it to show signs of fatigue as well. It's the whole package that you need to look at. If you are going to do it.......do it right!
So what do you think?
Micah
P.S. If I were you, I would rebuild the engine wtih the Holley Systemax II package only. It cosists of a Vortech-like upper/lower intake, head/cam package, new timing gear/chain, and ARP stuff. You won't need forged internals which will make your engine rebuild cheaper........and all you will need is a MAC intake + C&L 73mm MAF ($250), 24# injectors, 255lph pump, headers and exhaust. And you'll see 350HP, 350ft-lbs torque.
Install a build AOD, matched stall, and 3.73 gears and you'll have blast. BTW, the Holley Systemax II kit costs $1900 BRAND NEW!