With these fish, you might be able to do 2 jewels, 2 acara, one Pleco.
That was not my intention to give misinformation at all, just they seemed like huge fish based on a google searchNot to be rude but go to google type in acara or aequidens species see what you like then see what you can get from places in your area or www.tangledupincichlids.com or wetspot.
An 11 inch poly can absolutely thrive in a 75 gallon tank. These are not incredibly active fish and do not require the foot print you are suggesting they need. Any upper jaw besides weeksii, teugelsi, and ornate would work in this tank. I know a 12 inch fish seems big but they really dont require the same space as a 12 inch cichlid, very easy to keep in groups as well.
That graph is highly inaccurate (not your fault) i remember seeing that yrs ago and thinking my god they get huge. Wc Teugelsi can easily get over 20 inches, i would sooner see big foot than a 16 inch sen and i had a del that never passed 9 inches.
I think that list may have some measurements taken for specimens on collecting trips. Op will most likely be getting captive bred fish which dont get nearly as large as wc plus there are quite a fee wc polys that would be fine
Hao your the congicus whisperer how many 39 inchers have you seen in aquaria ?
T thefredpit can you post the size chart agian sorry bro
