I have a single male firemouth in a 75 with some tiger and cherry barbs and 3 emerald cories. He's fine with the plants. Only thing if I had it to do over, would be buy some different cories. He was in the tank first, and was quite aggressive with the cories when I first put them in. So much so that I gave him a three week time out by himself in a 20 gallon. Since re-adding him he's doing a lot better. Still gets after one occasionally, but it's more of a get out of my space thing now. Before he would chase them relentlessly - with bad intentions.
Anyway, I said all that to say I think albinos would do better because they are much more of a contrast in looks to the firemouth. Pretty sure that what triggers his aggression.
Good luck with the tank. I really like the hardscape.