Paul,
Jerry Hey is your man on the PP rotor housings - the original 13B ports are filled with high temp epoxy to seal them off and fill the cavity. Someone somewhere said the cavity really didn't need filling - I'm personally unsure!
George ( down under)

Guys, The ports don't have to be filled with epoxy, that is just one way to do it. They must be closed off somehow though. Some people just put plates over the openings which can be safer than epoxy for the long term. The best is if someone builds aluminum end and intermediate housings.
Bill Jepson

 

Bill,

Do you mean something like this, see attached.

George (down under)