chain saw them down to the biggest size your band saw will handle.
I put a 6" riser on my Grizzly 14" band saw so I could cut some pretty large burls.
You have two choices now.
1. Wax them up and put them to the side for a year or two. The moisture will slowly evaporate. If you don't wax them, expect 1/3 loss due to checking.
2. Cut them to slightly larger than block size, let them dry to the moisture content your stabilizer will work with. Expect some loss due to checking. After they come back, cut them to final block size.