What heads and cam are you running? What rear end ratio and transmission are you running. You don't want the stall to be higher than your cuise rpm in top gear.

You'll probably want to talk to one of the converter manufacturers. An off the shelf converter will probably stall at a higher rpm than advertised with the torque of the 408w.

 

A 9 1/2 inch 4000 stall converter with 4.10 or lower gears is pretty comfortable for street driving. Much above that and its more difficult.

 

Hydraulic Flat Tappet, Advertised Duration 268/ 280, Lift .510/ .512,
Iron Heads with 2.02in 1.60ex
3.89:1 , 9 inch
Hp c4 with 67 valve body and shift kit

 

I would go around 2800 with that setup.That's not a lot of cam for 408 cubes