I think your stocking suggestion sounds great! Be careful with the Demasoni because they can be pretty aggressive. You may want to add a few more Acei to the mix as they like to be in larger groupings. I would recommend 4 of the Acei and 4 of the Labs.
I would suggest 9 more demasoni, 12 are fine, 3 will end up as 1 over time. AND an aquaclear 500 HOB, or something similar, to handle the bioload.
The labs and acei would be best as trios or 1m/3f each.
Weekly water changes too.