SLR = single lamp reflector, meaning there is an individual reflector around each bulb.
The 4x80W retrofit should work fine, stagger the bulbs so the whole tank is covered. The ends will be slightly darker, but it should work fine.
I haven't actually seen any data/tests that show actinic bulbs are no good for plants. They are really blue though, I don't like the appearance. The 10000k Catalina bulbs are slightly blue, the 6700k are slightly yellow. I would get 2 of each.
I would e-mail them to make sure the 4x80W retrofit kit has the individual reflectors, it doesn't list them in the description.