HI Madman
g'evening...
well it sounds like your getting the nitrates down..BUT they are still at toxic levels and you really should do another partial change right away. I know its a pain to do all these water changes, but with those figures, its so important for the sake of your fish. Congrats on getting the 55! nice... And you bought some "bio spira" to cycle the tank right away. Good for you. Just follow the directions on the bag and make sure that you keep that stuff in the fridge, as it goes bad if not kept cold. I think its a great idea to add it to your problem tank, but do the water change first. Since you shouldnt do any water changes ( i think..) for a week after you add it. And with the levels so high, you really do need to do that water change again asap.
Good luck!

~ kate