They do indeed dry slowly, very slowly at 80 F. Heat speeds it up. To get such thick pieces dry in a month or so, in the kiln, you need no less than 150 F and around 44% RH or 6.5% EMC. Even then, the shell will be drier than the core unless you wait a bit longer.
Do you have an attic? If so, storing (drying) a few pieces in the attic will work if they are not to heavy for the roof trusses.
To check the MC, use a moisture meter with insulated 2" pins, such as a Delmhorst with the 26ES electrode. I prefer a digital meter.