I am a newb to the sight and somewhat new to Mopars in general so please excuse my ignorance if this is a common question. What is the best way to squeeze 400+ horses out of a 383 but keep a mostly stock appearance of the engine? Please be specific on the recommendation of parts.

Are you going to use cast iron heads or aluminum heads? It is a lot easier to make more power with a set of aluminum heads but if you need to keep the engine original looking then you're stuck with cast iron.

Compression,ported heads,and the right cam for exhaust manifolds.

Was thinking about headers, better carb, intake, cam but not sure about aluminum heads or cast iron. Engine doesn't have to be stock for judging I just want to keep with the overall originality of the car but make enough power to plant the passenger to the back of the seat.

Start with a RB crankshaft offset ground to have BB Chevy rod journal sizes and a 3.91 stroke, bore the block enough to straighten the bores up real well and have the mains and counterweights turn down on that crank to clear the 383 block That should push your passengers WAY Back in thier seats You will probally have to have a custom piston made for this deal, make sure and figure out exactly what compression ratio with which set of heads you want before ordering the pistons Using a BB Chevy type H beam steel rod work very well in these appications also

400 hp is fairly easy to do if you're willing to buy a set of Edelbrock RPM heads and some semi-custom pistons. What you want is something close to 10:1 compression with zero deck, a 0.036 head gasket and the closed chamber heads. Use a Performer RPM intake manifold, a 750 carb and a mild cam and you'll be there. The Mopar .528 solid is probably too big for a street driven 383 but it depends on how heavy the car is and if it is a 4 speed or auto.

You can do the 440 crank trick but it costs more and makes 500 hp which is 100 more than you're looking for.

Not sure what the HP is but my 383 runs pretty good. It is in a 3650 lb. 69 Super Bee, old school TRW 12.5 to1 .060 over pistons,Lunati .507 cam, street dominator intake, 750 Demon carb. with Mopar aluminum 452 heads, 4 speed with 4.56 rear. Has run a best of 13.16 at 106.72 with a 2.25 60' at 5800 ft. I know there is a lot left at the line. And this is pretty much a 30 year old build other than the heads.

If you want a stockish look go with 440 Source Stealth heads (Edelbrock knock offs that look stock). An Edelbrock RPM intake (fairly stock looking), headers (any that fit well) and a decent cam (Hughes Engines sells Mopar specific shelf cams), u could make 400 HP easily, probably well north of that. I think the biggest hurdle is finding Pistons with a decent compression height. This is overkill but there is stroker kit for a 383 (440 Source sells one along with other vendors) that uses a 4.25" arm, 6.535" rods and a 1.32" compression height piston that is easy to get to a zero deck for a quench build. It ends up being 496", definitely overkill for 400 HP, but an easy recipe for 500+ and have a stock look.

Exactly as he said. The first engine in my Lebaron was almost exactly as Cab described. .030 over 383 block, 3.900 stroke 440 steel crank, .560 flat tappet cam, ported 915 heads, zero deck flat top pistons, 6.385 eagle rods--+.250 long chevy rod, but Chrysler width,[eagle makes them that way]. Went 9.02 at 149 mph at 2450 lbs. Close to 700hp. Engine was built for a Super Bee that I sold, so since I already owned it, I put it in a race car. Camshaft broke and bent most of the valves after 3 full seasons of racing, 1300+ passes. It has been fixed and will be going in a 72 Rallye Charger street car.

Are you willing to stroke the engine or do you just want to keep it at 383 cubes.
Of the engine mods, and keeping it fairly stock looking, what parts are you OK with being changed out for aftermarket parts?

Getting to 400HP with 383 cubes to start isnt so hard as compared to a 318. A basic hot rod combo would be something like a;

750 carb
RPM I take
Mildly ported heads
At least a 9.0-1 compression ratio
Cam @ 230@.050
Headers into a 2-1/2 exhaust

Equipe the car with 3.90's/4.10's, a shift kit and stall converter to match the combo and you'll have a nice and decent basic hot rod combo. The above combo creates an easy 400 with a 360.

Stroking the 383 helps with a nice jump in torque. And that is what puts people in the seat.
IMO, I would honestly look for a good bit more power to keep people in there seat. It just add's to the awesome-ness of the experience. It will make for a memorable ride.

Where you at in KY?

We have some good mopar guys.

So, as a group, we have you building a stroker motor with aftermarket heads to do what otherwise has been done in the past, for decades, with a good overbore/machining, known compression, port work and solid flat tappet.

Curiously, what size budget envelope are we breaking here??

As Dean says, what's the budget? What car?
Build for torque, HP will be there.
You can build a really strong 383 with the HP manifolds, just keep it at 9.0-9.5:1 esp w/iron heads. Good head work or a set of the Stealths (depends on what your iron heads need), a reasonable-duration cam with around .500 lift (Engle, Hughes, etc), Perf intake & 750 CFM. Strokers are nice for the hidden size, and they don't require loose converters or steep gears; but that might be out of your budget.
If you grind off the Eddy logos, paint the whole engine like stock and the carb is hidden under a stock air cleaner, it'll look stock & unassuming to most everyone...which makes it that much cooler when it hauls butt.

He can use the Speed pro 2315 pistons and the 75 cc Eddy head or the Stealth 80 cc head and machine/gasket for quench and be in the 10:1 range.

There is some good 383 info in the tech archives posted by Dwayne Porter.