Need some help with high torque 408 build

Honestly, the OE iron heads will fall short. For the price you'll put into them to have them perform, your better off with a set of Edelbrock heads prep'd and use a RPM & a 750 carb.

While this combo on a 360 is a bit more so in the higher rpm performing range, it is much more at home on a stroker. Remember your going up 40+ inches and it's almost all in stroke which creates torque. From 3.58 to a 4.00, this is a big torque maker. The big inches will gobble down the carb like a 600 on a 360.

Your cam is also ridiculously small.
Simply choose the cam to operate in the rpm range your going to be in most. Cane cams for example list a cruise rpm there cams operate in best for there intended purposes and cam size. Ask what ever company you intend to look at what there cruise rpm range is for a given cam your looking at.

The cam need not be big. You'll peel the pavement back.