Predator, Your concern for the well being of your fish is commendable. It seems as though you have learned one of the golden rules of fishkeeping. Sadly, there are very few LFS's that will provide you with the same concerns about your tank that you do. Most LFS's will encoruage, or at least not discourage, ill fated choices. A key thing to remember is that these stores are out to make money. As a recommendation, I would take a visit to a few different stores, without making any purchases, see what livestock they have available. Look at the quality of the livestock, look for things such as fish available for sale that are suffering from diseases such as whitespot (ich), fin rot, or other fungus'. A more reputible LFS will mark any tanks containing diseased fishes as "not for sale". Listen to information provided by the clerks to other patrons of the store. If you hear things that might sound a bit hinky, bring them up in a forum for discussion. you might also test the honesty of an LFS by finding a spieces of African cichlid and asking the clerk if they can go in with your tank with your community tropicals. If they say yes, then walk out the door. The answer to that question is undoubtedly NO!
Your water has a high Ph, while this is not necessarily ideal for tropical community fish, it is great for Tanganyikan Cichlids and Malawi Cichlids (African Cichlids). Now would be the time to reconsider what you wish to keep. Research your options thouroughly as down the road, it will be far more difficult to change your mind.
Best of luck, I hope this Info has been a help,
Steve