Just curious. Why wet and dry ? All wet biofiltration works exceptionally well and you might just make that tank a big biofilter, or sump, if you wished to.
I get the wet/dry filter was a bit of a fad at one time, and they do function but all wet works just fine and is easier too.
Most pumps list the gph
on the package, but some are a bit optimistic, some are a bit pessimistic about what gph
is in real conditions, so I'd try for one that allows a bit of adjustment in flow if possible.