Restocking my 60-gallon tank

[inquiro]

Hi everyone, I'm thinking of adding some new fish to my 60 gallon freshwater African cichlid tank as a surprise for my parents. They've always wanted me to mix things up a bit, and I've been looking into the Yellow Tailed Acei cichlid and Rusty Cichlid. To make room, I'm planning to rehome 4 of my Yellow labs to get a better male-to-female ratio.

I'd love to add 4 of each of the new cichlids, but since they'll be unsexed, I'm hoping for a favorable ratio. The tank has a good amount of rocks, and I'll be adding even more when I'm home to break up the line of sight and create more spaces for the fish. Does anyone have any advice on how many fish I can safely add without overstocking?

[inquiro]

As for the filtration, I'm currently using a Marineland Penguin 350B Biowheel HOB filter - it's been working fine so far. If needed, I have a spare one in storage or my dad has been eyeing a canister filter, so that's an option too if you think my current setup won't handle the extra bioload. The current fish are doing alright, not great, but alright - the tank's been running for about 5 years now and we've had some successful fry raised without any intervention, which is pretty cool.