Let's see if I can address everything in one post:
Kribfreak: I know the 29 is overstocked, but - as you stated - the "inch per gallon" rule doesn't apply for cichlids. I am keeping a close eye on the water and have the tank over filtered. So far, I've not really seen much of a problem. Most of the fish are still babies, the biggest one being all of 2 1/2 inches - so they've got enough stretching room - though I'm sure they'll still be happy to move to the 75.
As for moving them to the 75, that's a big no no - not until the tank finishes cycling.
Of course, once it does - I'm all for it., obviously since i bought the tank specifically for them.
semper fi: Thanks for the tips on adding the fish to the 75. As for keeping the moorii in the 29 - I'm a bit confused. My 29 is a tall, which means the footprint is that of a 20 gallon. Why would I want to keep one of my biggest cichlids (his adult size will be about 8") in the smallest tank? I think of most of the fish I have, he'd appreciate the 4' foot print.
As for the rest, I'm doing a fishless cycle, so I'm adding quite a bit of ammonia to make sure the tank can handle a big load from the fish. Once the cycle is done, I'll monitor the ammonia input and how well the tank is able to break it down before I add a single fish. This should hopefully address any concerns I have regarding how many fish I can add at a time.