a big block in a 4th gen car is just asking for trouble. put an ls1 in your car and lt's, youll be touching both sides of the engine bay, and some how you want to cram a big block in there? good luck and i hope you have alot of money, buy and ls1 or lsx as a base engine and build what you want from there. but i hope you have alot of time and money. at 800 hp you will never be able to nicely street drive any 4th gen, ever i promise. thats whay to much power to just nicely cruise down the street if its n.a. now if we are hitting that with turbos maybe, id jus say think this throught, you need more plans

 

I suggest you take a look at this article and consider even with a bottomless parts bin and many thousands in labour, they still ended up with "only" 638 hp

http://www.lsxtv.com/forum/mission-i...red-2809.html#

 

for the price of that engine alone, i could be running a boosted LQ4/LQ9 at about 750-800rwhp. and i wouldn't have to swap to a forged crank and rods either. just the pistons. oh and i can throw boost at that block like it's nothing, an LS1/2 block wouldn't hold the boost.

if you built it all yourself, i could see around $6k-$7k total.

 

with just the cost of that ls9 you could put and ls1 in the 8's...
granted its cool, but its a waste of money

 

It would be cool once it's done, but man what a lot of time and money (and sawzall blades) it takes.
Here's a big block 4th gen: http://www.cardomain.com/ride/634484

 

That's cool. Amazing that they managed to get it to fit and actually driveable.

 

If you have the budget, look at the LS7 (427). You can put a variety of supercharges on it and achieve your 800 hp. The "not being able to nicely street drive it" part is nonsense. A friend of mine has an LQ9 with an F1 Procharger and street drives his just fine, and that car is making around 900 hp. Another buddy had a forged LS1 with a D1SC making 700+ and drove his on the street just fine as well. I make around 600 to the tires NA with a solid roller 408 and mine drives on the street just fine- so don't worry about that. With the right combination of parts and tune you will be fine.

As far as rears are concerned-one of the best ways to go is to buy a FAB9- again expensive. Another option would be a 12 bolt,etc. Make sure you purchase a good clutch- Textrailia, RAM, etc. I have used both the Textrailia Exoskel and the SPEC stage 3.

Like the others said, to do this build right you're going to have major money wrapped up in your car. If you can compromise with not having a 427ci, look at the LQ9 iron blocks. You can achieve those numbers out of a 402/408 with a blower or turbo easily.