The oscar will be very happy in a 75, ditto for the jacks in the 150 and probably the labs in the 40. More room is almost always best with cichlids.
Flowerhorn might be okay in the 150 with the jacks, maybe the oscar with the jacks with the flowerhorn in the 75.
Temperaments do vary some, it'll probably take some experimenting on your part with close observation. You shouldn't have any problems now, but may as they mature. Until they mature, you won't know what their adult temperaments are like. My inclination would be to keep the flowerhorn alone and the oscar with the jacks. Oscars are not so much aggressive as adventurous eaters(Can I eat that?) in my experience. Flowerhorns are generally more aggressive and can be insanely aggressive.