I have a 440 in a e bod,lunati 303 cam,worked 452 heads,391 rear auto.
has 3/8 sender,fuel line,eddy mech. pump,eddy rpm intake,850 holly dbl. pumper msd 6a ign.,headers,2 1/2" exhaust. runs like a champ and falls apart just a tic past 5 grand. I've tried jetting,timing,fuel pumps,no air cleaner,gas cap,2 different dizzy's all with the exact same results.
I would think it should pull past 5 grand but cant figure what's hanging it up. seems to be fuel but plugs are a nice tan color.
Any idea's??? I'm stumped.

Not knowing whether you've performed the mods to the car, or purchased it that way?....but any chance the MSD may have a 5000 RPM rev chip limiter?

May be running out of fuel. run it up to 4800 let off completely then back to the boards if it then pulls up to say 5500 then you know your fuel is not keeping up!

i've got a stock 440 magnum that drops dead at 4500,... .

heads been cc'd to 85 so a little cut,can see the numbers shaved a little bit. no rev limiter. didn't think of backing out and hitting it again but will try. just running stock rockers for now.
I did not build the engine so not much help there.

maybe a set of rocker shaft shims???

As you know I'd want to pin it to fuel or ign first. Sounds like you have a killer fuel delivery system but I'd T at the carb inlet & run a neoprene line to a vac gauge with a psi side & tape it to the windshield & need several psi at the offending rpm/load. since you've been dealing with this for awhile I'd go ahead & go to the trouble of subbing in a regular electronic ign & see what happens. Is rotor phasing close enough? NAPA has an Echlin rotor with a .060" longer blade that doesn't fix phasing but helps it as it reduces the distance the spark has to jump. MO-3000 for $8 dollars & change out the door. As said check preload. I'm gonna WAG that it is the Might Sputter & Die system. Holler how it goes.

do you have a carb spacer?
maybe the fuel is boiling?

I have had a bad coil cause this kind of trouble.

Cam timing? My son had a 2.2/TII that was a tooth off on the cam sprocket. Engine ran GREAT except above 5,000 or so.

Obviously you have hydraulic lifters..
If original Mopar OE stockers 5K or a little over is all you will get...

Just my $0.02...

Don't overlook valve springs.

Shims may help try the fuel test first.

That was the first RPM limiter I ran into back in the day next was valve springs.

What happens when you rev it with no load (park/neutral)? If it still won't go past 5k then it's almost certainly not fuel supply

I'll go with valve springs, if you are running stock rockers and springs it's a wonder it runs at all. Next would be coil although those tend to work until they get hot then they don't work at all. Alsomake sure you are not sucking the choke horn shut.

We had a 383 falling flat like that. It was the fuel pump pushrod. I second or third this opinion. Just looking at the rod you can't tell much of a difference.

I'd change that and see what happens.....