Flash guns

I have done a little search, but not to what i want. I have a bronica RF 645 and a Bessa R. Now i do use a little practica flash 1600. With a X stop from 8 to 16 give's me a fill in falsh. But there has been a post for the use of a Nikon SB that is more usefull.
Any taker's on this one please, i am to do a baby shoot very soon, i will be using 400nc or 160 (Kodak), any thoughts greatly received.

Regards Graham

If it has an auto mode set the F/stop on the flash to 1 stop more open then the lens. Assuming you want a 1 stop fill. You can also play with the film speed on the flash if you can't get enough adjustment from the flash.

Is that what you're asking? Fill flash?