Manual Valve Body

Can someone give me some opinions on a manual valve body? I have a '68 Cuda with a 408, dynamic 3500 stall conv., 998 tranny, and 3.91 gears. I would really like to eliminate the kick down, however I have heard both sides good and bad. This car is just a weekend car and occasional drag strip times. I won't be driving on long trips, just around town. Cam is a Hughes custom grind 242 and 246 @ .050 lift roller grind.

Thanks,
Darren