There are tank builders who will build to your spec. Not sure on cost, but I am sure it is high for something one off.
Yes I am sure that if you want to THROW enough money at someone like RCI they'd make you any size & shape tank you want but the Dang Nab GenRight tanks are spendy enough. There's a lot of other things I'd rather spend those funds on.
I've been looking and talking for the past few years at all the different performance sites about what cam to run in this engine when it's all said and done. Now I really don't care to see my peak RPM's get much above 5,500 and HOPE I don't see much above 5K.
So choices are not many when it comes to the magnum V-8. Of course Comp Cam, Crane cam & others will grind you a custom cam but I wasn't ever sold on getting one of theirs. And so for those of you who are looking at what engine to choose just remember that Mopar is the red headed step child.
UTAwesome Performance is the company I have decided to go to for my cam. http://utawesomeperformance.com/index.html
The cam I'm going to use is their purpose built cam for stroker 408 engines. http://utawesomeperformance.com/store/p38/UTP_408_Camshaft.html
Here is the dyno chart from this cam.
Advertised Duration 288 intake/294 exhaust split pattern high torque
Duration @0.050 236 intake/242 exhaust
Lobe Separation 108 LSA
Lift Intake 0.347" and Exhaust at 0.360 (0.544/555" with 1.6 roller ratio)
75 Degrees overlap