Amey, that weight was the first thing that went through my mind too. In the kit building forum I posted some photos of my Swoose float plane on land LG I just got to maiden yesterday. It came in dead on 8 pounds and I have a YS 1.10 four stroke in it. Keep in mind it's a gull wing with a flat bottom, nothing stunt about it at all. To my surprise the plane did the few stunts I tried quite well. I did a stall turn and it did pull straight up but I didn't try to hover or pull it up from a hover.
The reactor should have more lift then this swoose but I do question it as a 3-D plane at that weight? All you can do is maiden it and see how well it is going to work for you. The Reactor is a great flying plane. You know I'm not a 3-D pilot but I have flown the Reactor and like them. With your engine it may very well be an outstanding 3-D plane? I was both happy and surprised at how well my 8 pounder flew. The weight was on my mind too but it turned out to be no problem. I will bet you will be OK with it.
Good luck to you on your maiden. Take a lot of photos and start a new thread for us when you do.
Gene