I don't know of any prepacked HPLC columns that have a boronic acid resin. But if you can pack your own column, I recommend using immobilized boronic acid from Pierce:
800 kDa you can nicely separate by using clasical size-exclusion FPLC, by WorkBeads 40/10000 SEC o Bio-Works. This is an agarose with extremelly big exclusion limit 10 MDa. Have succesfuly used it in my lab ffor 3 MDa huge complex. Alternatively Superdex 200 or ENrich SEC 650 columns can be used, but there you will have your complex not separated from agregates. Hope it will help you.