J.:
You can/could use the timbers you have milled to create your braces. Many a frame has been put up with pine braces. And as you have already milled the stock you can/could continue.
You can use them with a 1 1/2" tenon and a 1 1/4" shoulder. But you may want to take a look at the proportions. What I mean with an 8x10 post a 2 3/4" x 8" curved brace might look to small. It's your house and you're call. It may look fine. Most timber frames are engineered to not take braces into consideration, in regard to supporting the upper horizontal member. They are usually considered to be used in compression and in that regard they should be strong enough.
To visualize the results of using these braces you could take a sample post and cut a brace pocket in it and then create a brace and put them together, raise it up and stand back and take a look at it. This may help you to decide if it looks to "skimpy" or not.
Good luck with your project.
Jim Rogers