I built my two Shark 45's by copying the Jetco Kit and there are a few things to consider. First, I made my fuselage sides one piece by making them 3/8" wider that the kit pieces. That will help you build a straighter model rather than trying to align the front and rear halves on the wing. Next is the engine. Find out as close as you can what your fuel requirements will be, and measure the nose to be certain you can get a large enough tank in there. I moved the rear bulkhead all the way back to the wing leading edge so I could get a 6 ounce tank in mine. I used the late model ST.51 in mine, and they weight 11 ounces, I think, so if the K&B .61 is 14 ounces, be prepared to add tail weight if necessary for balance. Both of mine balanced out pretty well without any extra ballast needed. Landing gear length will need to be considered if you are going to use 12" props, so I made my landing gear removable so I could change the length if need be. And this also help when packing the model for a long cross country trip to VSC! Good luck with yours, I think you'll like it.
Type at you later,
Dan McEntee