Advice on VTOL build

Hi Guys
I am newly joined, after searching for information to help me with my project this looks to be the best place to ask experienced people questions about drone builds and issues and join in with this fast growing hobby.
I am about to start a build of a gas powered VTOL plane, I have a general plan which I have made by taking ideas and information from various professional built drones and other hobby builders, I am going to build a balsa kit of a fixed wing drone and adapt it to my idea, I have chosen to build a balsa kit as it will allow me to run cables and strengthening along the wings for the lift motors and ESC without the cutting channels that would be necessary in a solid foam wing. This is where I start to need advice, I intend to fix 20mm od carbon fibre tubes across the wing in line with the fuselage held by 20mm tube clamps, on the end of the tubes I will fit CNC motor mounts, I would appreciate some assistance with the fixing and positioning of the booms, no doubt to arrive at this position it will be necessary to know what motors, propellers and battery will be used, this is another area in which I need some advice.
In order for you guys to be able to help I have listed as much information about what equipment I intended to use including weight where possible.
The plane is the AAI RQ-7 Shadow from Hobby King Weight: 3971g SKU: 9099000065-0
The gas engine is the RCGF 21cc twin engine from valleyviewrc,com SKU 0000885 all up Weight 950g
Long range mini receiver by Dragon Link 10g
FPV1013 V2 1.3GHz video transmitter SKU: 0101-24 90g with camera
1/2 litre Fuel tank + fuel around 400g I am not sure if this is to large or not I will research the engine and find out what the flight time to fuel requirements are.
To take into account things I have not included an onboard weight of around 6Kg would be a reasonable starting point this does not take into account the 4 electric motors and ESCs.
I hope this information is sufficient for the experienced drone builders among you to help advise and guide me.
I look forward to hearing from anyone who can give me advice and perhaps alternative ideas, and thanks to everyone who take the time to look and reply.