It is not carby as you can clearly see it has got fuel injectors, and sensors so your first concern is sorted out...it is an efi engine and not carbi.
Now that you have bought this car, you should use it the way it is as long as it is not giving you any trouble.
After driving it for few days you will be in the best position to comment if this engine goes well with civic or not. By the way if this engine is 1500 cc it should be able to cater the power requirements of a 99 civic chassis...