Before jumping into that frontosa boat check a couple of things out.
1. Your water comes out of the tap at a high pH but is it buffered to stay that high? With poor buffering the pH will have a strong tendency to drop rather quickly and you may find that you are constantly fighting a low pH problem in the tank. Check the alkalinity and hardness.
2. Fronts are notorious for taking a long time to mature. If you start with a group of youngsters you may be looking at 24 months before you see any breeding activity. Not exactly the cash cow that some may lead you to believe.
3. Are you really excited by keeping fronts? If not you will become restless and unload them well before they get close to breeding age. I have found that if I buy a fish 'just because' I never keep it for long. Get something that you really want.
4. If you do want a breeding pair of something, look into fish that are smaller and less aggressive than Jags or Devils. Even in a 150 there is oft times not enough room for a female to escape the attention of a love crazed male. A 10"-14" fish finds it difficult to 'disapear'. You'll end up with a large piece of ugly eggcrate in the tank or worse yet, a dead fish. If large fish are absolutely a requirement go with Oscars or such mellow fish.
5. You could go with individual specimens of several species but the downside here is you usually end up with one decent fish and several haggard looking ones. The fish have a tendency to fight and pick at each other which typically leads to torn fins. Your fish will not dispay the awsome finnage which they are capable of growing because it is always getting tattered and torn. Take a look at Mojo and Cichlid Scene's fish. More than likely the fish that make you say WOW! are in tanks by themselves with no chance of getting a torn fin. Show fish are typiaclly raised individually to ensure perfection.
5. Consider a pair of smaller cichlids like salvini, bartoni, nicaraguense, fenestrata, labridens, firemouths, etc. These grow to 8" max and will have more elbow room to coexist. Many are spectacularly colored as well. They are tough and can handle your water parameters. The tank is large enough that you can even add a few anciliary species to create a 'community' of sorts. A large pair of spectacularly colored
meeki sheparding fry about the tank, a large school of mollies hanging out at the surface of the tank, a couple of sailfin pleco or even albino bristle nose, perhaps a few large giant danios to add zip. Decorate with lot's of bogwood and large stones. Now you have some gorgeous fish that will act in a more natural manner, a nicely decorated tank and lot's of fish to give you a nice visual presentation.
I guess you have to decide what you want:
Big Tank - One Big Fish
Big Tank - Pair of Big Fish - Ugly Decor (eggcrate divider)
Big Tank - Big Pair of Mellow Fish
Hope this helps!!