Hes my simple as possible common sense advice:
Dont worry about complex calculations and using juggling impedences to extract the maximum power from an amp, any of the following will do just fine:
A single 4 ohm cab.
A single 8 ohm cab.
Two 8 ohm cabs in parallel (the default wiring scheme for amps and cabs with multiple connectors).
Yes two 4 oms in series technically works as well but ... why would you ? its fiddly needing custom cables an less effecient than 2x8 in parralel.
Dont obsess over driver size, the design and quality of the cab is much more important, any good 10 or 12 loaded cab can produce the necessary frequency range.
All other things being equal more speaker cone area moves more air using less amplifier power irrespective of whether this is achieved withing the same cab or multiple cabs stacked. 2 * 10/12 drivers should enough to get a decent volume with a mid powered amp like yours.
Dont worry about over powering the cabs, really just dont so long as your using one of the configs listed, actually damaging any half decent bass cab with a mid powered amp is very hard in practice unless you are deliberately setting out to abuse it (and if you are abusing it having an amp with a lower nominal rating than the speaker is not an absolute gurantee than you wont do any damage).