no! pr1.3 is closed maemo stuff and ubuntu != maemo.
you can however with a /capable kernel/ copy the whole pr1.3 stuff and everything else from maemo to the ubuntu and boot that. that works .but that actually is replacing ubuntu with maemo so that it is no longer ubuntu but maemo with some parts from ubuntu. further you cannot make it available for the public as it is cruftware.

and as a sidenode: while running different binaryformats is possible it is not totally stable so might break sometimes.

EDIT: in more understandable: it is illegal for ubuntu to use pr 1.3 so you can't use it. nokia forbids it. plain and simplified.