RCM has plans for the PT-40. It is a fantastic trainer. And all the information you would need would come with the plans. You also get a reprint of the construction article. At a great price too. As far as spads go I will not comment. I have limited knowledge in them. I personally in your case buy the PT plans and build away. Your second plane could be a spad. Then you would get experience in both worlds. Good luck whichever way you go.

Mark Shuman