Have fun! I had a blad putting y A3000 in a Elbox tower! Its a great system. I agree the A4000 version is a bit small. It came out first is all I can think of for the reason. As long as the Mikronic one will accept the boards and line up it should be a simple process. Just do as the others have said for cooling. Have a good fan taking air into the tower at the front bottom of the case. Then put at least one more at the back top of the case.
