PDU to 7-bit

I know this sounds rather newbie, please someone have the
patience to refer me to a document at least.

I've got 8-bit PDU's already constructed and ready to send
to telephones. Logos, tunes, EMS, you name it.

Kannel sends as UDH + 7-bit text, split into SMS.

Or does it? Is there a set of config switches I can use to
either send the 8-bit PDU as-is, or have Kannel
internally convert all to UDH + 7-bit user data?

Is this done as an OTA send? I can't tell.

This is probably an FAQ, but after spending all
morning reading specs I can't answer it.

Thanks in advance,
Steve