Actually, your stocking could work if you have good filtration and do good maintenance. Loaches are mainly bottom dwellers, angels, barbs and gourami are all over, plecos tend to hide.
Eventually, due to size and aggression, you will need to re-home an angel or three. Ideally two in a 55 is the maximum you'd want. Since you stated you are putting up the tank, I'm going under the assumption that you don't have the fish yet and will be buying stock from your LFS. Most angels are about nickel to quarter sized in the stores. That is the only reason I'd ever say this would work for little bit.