What about soaking stabilized rice bran with beet pulp and alf/oat cubes (or pellets, or timothy/alfalfa if you can find them). I think it's better than senior feeds with corn and molasses and it should add some extra weight without quite so much energy.
The safe starch and safe choice are both good bagged feeds (the first is triplecrown, the second I think is purina), and if you're on the west coast I've found the LMF products to be far superior to purina. LMF Gold would be my recommendation, possibly Showtime G.
I'd choose oil over cool calories, since it's made of partially hydrogenated oil (trans fat). Flax oil or sunflower oil are good choices.