The "firecracker" term is typical used to describe Tropheus moorii "Moliro"
All in all you do have 7 fish. Since the Duboisi still have the spots, I am going to take a guess that all 7 Tropheus are juvinile and less about 2.5" and are more likely in the 1-2" range.
These 7 fish will be ok in a 20 Long, with a Aqua Clear 110 powerfilter, and weekly waterchanges of 50%. But..you need to be planning on putting them into atleast a 55 gallon within 1-3 months.
Keeping Moliro's and Duboisi together is absolutley no problem in terms of interbreeding. When the fish start getting their adult coloration and start reaching a size of 3" or more, I would do everything possible to try and make the Duboisi total 8-10 fish, and the moliro's atleast 12 fish.
This will make your group size eventually be 20-22 fish, which will require atleast a 75 gallon in the future. I would plan to have a 75 gallon within 14 months.
If you choose not to expand this group, when the fish start getting to over 3" your going to have a problem with agression if the group contains more than one male for each of the two types. They will kill each other. You might get lucky, and have only 1 male in each, or get really bad luck and have all males. You will not be able to really sex them for certain till about 3.5"
I am not sure what your local fish store has for selction or price of the Tropheus you have now, but you can check out the retailers section and find a supply of Duboisi or Moliro rather quickly, and even with shipping will more likely beat a LFS store price, unless he was supplied by a local breeder.
Tropheus are expensive, but with online retailers, and breeders in forums like this that might have shipping availible, you can purchase them at a much reduced cost. So, dont be discouraged by pricing.
Check out your local paper or Craigslist and you could find a 75 gallon really cheap.
For filtration on the the tank, I would go with (2) Aqua Clear 110's and that would be your cheapest filtering choice. Clean one filter one month, then the next month clean the other one, and still perform your weekly waterchange.
Before you start all of this really, what was the issue for why your wanting to remove the Tropheus from the Peacocks 60 gallon?
If it is a diet concern, dont be concerned about that. There are some really good foods that both Peacocks and Tropheus can thrive on given proper acclimation for the Tropheus.
Is it agression, or something else?