I'd aproach it in reverse. The datasheets for CALB 40Ah cells say 12A recommended charge. I wouldn't charge over that, so do a 0.3C charge. So 12A on a 72V pack is about 7-900W. So just about anything over 800W.
I wouldn't try to quickly charge these cells, especially without a BMS. One cell can (and will) charge quicker and overvoltage.... if it does that, while the others are slowly charging, the cell WILL go thermal. These cells are meant for low current charge and a 3-4C discharge continuous. Don't go outside of those specs or you'll really risk losing cells, either all at once, or one at a time. Keep it at 0.3C or close to it. No need to go 220V input, just get a 120V 1000-1500W charger and call it good. I've got several models available if you want, both 120/240V (they autoswitch) programmed for your pack.
If you go the other way around, and want a full charge in 2 hours, you need to put about 3328Watts (approx size of your 26s1p 40Ah pack) into the pack if you discharge to 100%, which you shouldn't. At that much energy, you'd want to do about 1600W per hour. But the first hour needs to be more because as the voltage increases, the current decreases once you hit CV. So I'd size to something like a 2000W charger. Now, 2000W at ~72V lets say, is going to be about 28A, or about 0.7C, over twice the recommended charge current.
Risky, but it's all your decision. I'd keep it under 1000W. You underdesigned your system, I wouldn't push it!