I am going to say no, 2 550/600 size brush motors will not fly this plane the way your setting it up. Combat Models makes a heavy plane to start off with and they suggest to glass it as well, which you would definitely want to do if for the durability needed to handle the extra weight. There's alot of extra weight involved in the retracts alone. Every 1/2 ounce is crucial, your battery pack weight alone will be near 3 lbs if you use nicads, very expensive if you get the near 2 lbs of lipos needed to service 2 550/600 brush motors. This plane could easily reach 8~10 lbs going this route. Even if it did fly, it would be slow and always near stalling, not able to perform aerobatics, not able to gain altitude, a poor flyer all around.
A better option for twin EDF would be to go brushless. These motors are smaller, lighter, more efficient and much more powerful. They use smaller, lighter batteries so your weight is drastically reduced and along with that increase of power. This will be rather expensive, so thats something to consider.
Now if your dead set on using twin 550/600 motors, you will have to go minimums. Fixed gear, but most likely no landing gear(a belly lander) which is rough on the plane if your not flying on lush grass. For the belly lander version, you would need to glass the the bottom of the fuse with a few extra layer and especially on the wing landing gear fairings, along with any other contact patches. Also, you would still want to go lipos, the less weight will not only help this plane fly better, but also cause less damage while belly landing.
The last option would be to just get a single Jeti 45/3 or an AXI 2820 or 2826, and mount it on the back where the glow engine was suppose to go. These motors perform like glow engines ranging from size .40 to.60, there are even bigger AXI motors available, but you may have to use 3 or 4 bladed props. This way if you went with lipos, you could really build the A-10 however you wanted.