Standard seat tube and head tube angles are both 73 degrees (because that's what I like). 72 degrees is also common. I would expect most road bikes to be somewhere between 68 and 75 degrees. One source of this information is manufacturer websites.

I don't know if you can get a free version of rattlecad at this time. There are demo versions of bikecad https://bikecad.ca/bikecadpro (at the bottom). Not sure what the limitations are, it might work for you.