Those heads that the 400 came with are some of the crappiest early heads around. To make that 400 make some power you'll need a better set of heads with steam holes drilled (any machine shop can do it) and nice cam.
The factory 400 SBCs are externally balanced and have short 5.56 inch rods. They will make alot of power,but If I was even going to do the swap I'd switch to a crank thats can be internally balanced cheaper and switch to at least 5.7 rods and pistons.

 

Someone said something about L98 heads or somethin like that, and my friend has a internally balanced 3.75 crank that I could use, after that it'd be 5.7 rods and 30 over piston heads then a good cam Sounds like a serious project motor, maybe I should just get it running for now lol

 

You mean... would a well machined 400 with aftermarket heads, 5.7/6.0" rods and good aftermarket parts make more hp and torque than a stroked LT1? Yes it will... it has more cid and more bore area, which is that much better for a 23º head with large valves.
Let's put it this way... you'd have a much easier time building a streetable 550-600hp 400 than a 383 at the same level.

-Mindgame

 

Forget the stock heads. By the time you work the heads you could have bought something decent.

How much power are you trying to get from this combination?

-Mindgame

 

They are not technicly a smog head, but they have a very small runner especially for a 400 ci motor. What is the casting # exactly? Most heads I have listed that came factory on the 400s that year are speced with a 1.94 int valve and 160cc intake runners. The large chamber is a dinosaur in design, flame propogation is horrible with those.

 

Actually the question was really stock for stock would the 400 out perform an LT1 but I'm seeing I'll need a series of aftermarket parts for it to.

 

No... the stock 400 was never intended for HP apps. The stock LT is much stronger and durable.

-Mindgame

 

I'll have to check the casting number on the heads, but I know they are like 76cc, I honestly don't know a whole lot about heads, I just know basic things. Although if someone wants to teach me I'd be happy to learn lol, like 160cc what is that?

 

That's the intake runner volume. You know, that part that goes from the intake manifold down to the valve.

Any decent 400 build is going to need a runner volume of at least 200ccs. Can't get close to that with the factory heads. Not to mention, the heads used on the 400's were just not good castings to begin with.
If you want to keep everything budget... then you might look at the Vortec heads and Chevy's new single plane intake for it. That'd get you moving in the right direction.

-Mindgame