Don't ofrget about clear Oregon pine or Douglass Fir for the wood. Therse are "structuraly" more like Spruce than Saligna.
Saligna (blue gum) has a much more inter-woven corse grain and not realy such defined year rings like the Spruce/pine /fir wood.
This in my opinion is not an issue at all, the other woods just look nicer and smoother to work with. I believe thet Saligna will be the cheapest of all the wood.NB!!! it must be wood with a moisture content of more than 8% and less than 12 % if used on a plane.Kiln dried usually works well.
When you go buy the stuff, get twice as much as you will need, in wood there is allot of "un-knowns" and a piece might look good on the outside, but not as safe when cut up.With just a few planks you can get far.
Take a plastic hammer with you and tap the plank, this will give you a good idea of the solidness and if any big cracks are there.
Stay away from the darker red collour saligna, this can contain more oils and have hassles with the glue bond. Get a good epoxy for wood like Aeroldite, Aerodux 500 or any aircraft stuff. AMT also are epoxy specialists and can help you. I used epdermix 372 by ABE ( with regular bach tests though!) and the L-18's wing was loaded to 1300 kg (4G)and didn't even "moan" or creek
IIRC the VP uses allot of Marine Ply, most timber yards sell it. I used the BS 1088 standard with exelent results.
Aircraft Ply you can get at plywood distributers in Mooi str. JHB. DON"T USE COMERCIAL PLY!!!! It delaminates.
If you choose saligna, look for the very light pink to allmost cream collour planks, they are the lightest.
When making a glue joint, try not to sand it to the final shape, rather plain it, it keeps the pores in the wood open for the glue to get a full bond.
Ply needs to be scraped with a hacksaw blade to roughen up the surface and then blown with compressed air and vacumed where a joint is made.
I sugest you get a coppy of the AC-43, specifically the wood section to help with the technical side of thigs like the "grain runnoff allowed, knots/pinnknots ect. The book will also help with the fabric. Don't look at only Ceconite, there are other
If I was building the VP1 I would keep it as simle as the plans state, no canopies, large turtledecks ect. A well designed/installed windshield will do just fine and keep it light.
Hope it helps.
T