AB upgrade question

Hey folks,

I’m a little confused about my options in regards to upgrading my AB ticket. I currently hold an AB Special with STCW RFPNW, BST, Lifeboatman, Adv. Firefighting, VPDSD/SA, Able Seafarer-deck endorsements.

All my time towards the AB Special was earned aboard fishing vessels in Alaska, all under 100gt. For the past couple years though, I have been employed working unlimited tonnage inland vessels.

I have about 500 days on vessels <100gt, which I used to get my AB Special. I now have about 400 days on unlimited tonnage inland vessels.

Can I just make up the difference between the 360 days for a Special and the 540 days for a Limited with my unlimited tonnage time?

Also…if I eventually want to upgrade to my AB Unlimited, what is meant by “On Oceans”? All my seatime is on saltwater, or are they looking for all time to be beyond the boundary line?

Thanks for the help guys!