The most important things I have found so far are great planning , patience, good references (which you have plenty of here), and a full scale drawing. The drawing will let you figure out exact neck angles, hardware placement, and every other minor detail. If this intimidates you, there are plenty here with CAD experience that can help you. The Hiscock book tends to be the bible of guitar building around, and for a extremely good reason. It helps you a ton and leaves with with very few questions.
I'm not sure you still want to make the body larger or not, but also take into account that extra size also means extra weight. So think about how you'll be playing, sitting the extra weight is barely noticeable, but standing for a gig, and your shoulder will feel it.
If you want wood to just practice on and not make a working body, pine is great. It is cheap, easy to find in many sizes, works very nicely, and when your done with it and are ready to discard it , it burns nice and hot in the campfire.