Reading posts on ClassicalPontiac.com and from the Pontiac related email lists I'm on, I decided a mechanical fuel pump would not be sufficient for my 455.  So I ordered a Mallory 140 pump and matched a Mallory filter with it.  Upgrading the fuel supply line from 3/8" to 1/2" and the return line from 1/4" to 3/8" would also be required.  The following pictures are some of my progress.

Original sending unit -  unmodified.

Original sending unit -  now modified.  Removed the the 1/4" return tube and installed the 1/2" diameter supply tube in its place.  The existing 3/8" tube will be used for the return line.  If I ever do this again I will use a smaller bend radius when making the new tube.

Brackets made for pump & filter.
Mallory 140 electric fuel pump and mounting hardware.

  I will take more pictures after installation.