Someone school me on converter/pump relationship please!

As far as worring about the stall speed my dynamic was a 3900 stall. It was unoticable as is my current art Carr 3500.

Here is something i'd liek to share that dynamic told me. They said they could make me a 9" or 10" convertor that would stall at 3800-4000 range. (where my engine made peak torque). hoever they recomended "a tight 9"" which would be more efficient than a 10" that stalled at the same RPM. In their opinion that woudl be better for street driving.