Greg,
$hawn as built a few and he knows how much the little stuff will get you. I have heard him talk about the nightmares he had.
I have not built a 408, but these are things I know from reads and friend's cars...
9.2 deck height, so you will need a new lower intake, possibly upper if staying FI,
Headers,
drop motor mounts,
oil pan, pickup, and pump,
new flywheel,
new balancer,
said 408 stroker kit with crank, rods, bearings, pistons, and such,
machine shop time for balance and block work,
front bracket accessories,
distributer,
gaskets for everything,
and the little stuff you never think about until you take the project on.
other stuff that might be....
cam and heads should work, but you'll probably want to match them to the motor,
hood,
head stud kit for any amount of spray or boost,
maybe push rods and new roller rockers for the new motor,
fuel system, like pump, regulator, and lines...??
I think the bell housings are the same for the trany, but not 100% sure,
oh and if your staying FI, injectors and matching mass air.
That is what I can remember at this time of the morning....