JMO,

Do some port work to the heads so you don't have to go stupid big duration on the camshaft. Having a 4 speed makes things easier with bigger duration cams as you don't have the issues with in/out of gear as with an auto car.

No need to stroke the engine if you are looking at 400hp. 400hp is not that hard to hit a 360, getting air IN is the issue and heads are the restriction.