I've ran and raced with MSD ignition for a long time, I'm a firm believer in using better parts than you currently need so I would say go with the MSD box and coil for the box you decide to use
I ran the big gold race boxes (404B,404C,7,7C 7A and the current MSD7AL2 with the proper coils on all of them ) on my serious street cars
On your deal a MSD6AL would be my pick with your current stock ECU coil Follow the directions for wiring it and the coil also