I think I see a full width center port; they look like 200S cabs. Hard to tell on my phone. Do the backs come off?
If they are 200S cabs it can limit your options for drivers because the port ducting can make it hard to fit large magnet assemblies. Those cabs only came with AlNiCo magneted JBL D140F's, and larger, wider ceramic magnets are often too big to fit.
Old AlNiCo drivers or new Neodymium drivers are your best bet I think.