Help!

[inaforty]

Ok guys I need some experienced help.
I lifted the motor off the transom to install the new NFB steering and thought I would remove the aluminum trim and seal/epoxy the hull/cap joint. I can't get the aluminum off. I drilled out the rivets. I try in one spot to slide a putty knife under the trim but it seems there is a white sealant under there (seems like 5200). Was the factory trim installed with a sealant? The transom seems very very solid and I thinking that maybe someone already went throught trouble of sealing under the aluminum trim? Not sure if I should keep digging or let it be? Also is there anything special about the rivets or could I use SS screws to replace the rivets?

I'll keep busy installing the steering and be looking for your replys.
Thanks in advance for any help.