5.9 magnum stock vs aftermarket heads for 400hp

[modart440]

Putting together a 5.9 for my 68 Dart. Curious on opinions about head choices/requirements to achieve 400hp. Fresh shortblock Lunati 711 HR cam airgap eddy intake 750 Demon carb Doug's 1 5/8's headers. Was going to buy a pr of Eddy Magnum heads but second guessing myself if there really required to meet my 400hp goal? I'm in Ontario Canada the Eddy heads end up close to 3k with tax. Or just build out the stock heads with some home porting ,improved springs for the cam and a quality valve job. Wondering if that could be spent in better places. Car is a Pro Touring build with great suspension /brakes etc . 518 trans and 3:55 gears
Thanks

 

[273]

Stock Magnum heads already can make 400hp

This is a stock 380hp crate engine, stock longblock M1 single plan 750 holley headers and something like 231/236, 288/296 108 .513 lift cam

 

[273]

Here's 300 hp crate stock long block and cam dual plane 750 and headers and Mod is ootb eddy heads and a comp 275 roller and airgap.

 

[pishta]

MAgnums.....No prob.

 

[moparmarks]

I've heard the the Magnum head with 1.97 valves out flow the X head with 2.02 valves.

 

[qkcuda]

Check your magnums for cracks first. How much are you going to have into the machine work to do the valve job, plunge cut the throats, new guides, shorten the guides for clearance and teflon seals, plus new springs, retainers etc?

 

[modart440]

Check your magnums for cracks first. How much are you going to have into the machine work to do the valve job, plunge cut the throats, new guides, shorten the guides for clearance and teflon seals, plus new springs, retainers etc?

150.00 200.00 tops lol thanks Dave

 

[qkcuda]

150.00 200.00 tops lol thanks Dave

Yeah, me too

 

[AJ/FormS]

And what happens if after you spend all this money and then they crack later?