Well, if your willing to put the time and money into your car... here's my recommendations...
First, get a shortblock from http://dynoflow.substorm.com/. Get a 355-406 shortblock with a 8.5 compression ratio and upgraded bolts. Slap on some AFR 210cc heads and a cam with around 250/
[email protected] with around .600/.600 lift. Any cam company should help you pick out a cam once your to that point. Someone else is going to have to help you with the EFI, I'm doing blowthrough because of budget issues. Next, I'd recommend either twin 62-1s or ~ a single 88mm turbo. Both leave you room to grow with your 1000hp goal. Since there isn't much 'bolt on' kits for sbcs, your going to most likly have to fabricate headers, and both your hot and cold side. To give you an idea on how much boost your going to need, 14.7psi @ 100% efficiency (most cars run around 85%) should double a engines horsepower. Since your engine probly won't make much more than 450hp alone, your probly going to need 20psi to get you to your goal.
If you don't mind me asking, what car is this going into? Your turbo setup and engine will probly put you well into the mid teens and you also have to keep in mind that your driveline has to handle all of this power. It's definitly doable but it will take time and lots of money to have it done right. An M5 is in incredible car; Beamers are definitley a smart route to go. My Parents have owned 3 and about to buy their third. It's going to be hard to find a high horsepower turbo car to get a chance to drive, but testdrive an M5 and see what you think and mybe some high HP turbo guys might chime in and give you their opinions. I will say that you'll have to put in a lot of hours to have a reliable 1000hp street car. You'll have to half throttle it around town in order to keep it in one peice :hammer: :hammer:
Goodluck though, turbos are definitly the way to go :cool: :cool: