Nice ride!. The cam is not the problem since my buddy has a 246/250 on a 108 ls flat tappet cam, ported victor, 10.1 compression in a 408 and it doesn't suffer from lack of low end in a heavy short bed dodge. His engine made 500hp/500tq and he has 4.56s with 30" tires, I think the 3.91s would be better for you. As far as the timing curve on the few 408s that went across our dyno
@Newbomb Turk found all of them wanted around 24-26 degrees timing at idle with nothing more until just after peak torque then an additional few degrees. This type of curve made the most overall power and added 15 or so hp at peak.