Greenhouses, Sheds and Sun Rooms - gambrel roof question....

im building a 12 x 16 shed in the backyard . the peak height is going to be 15 feet . im not going to use the standard angles for the roof because i want more headspace in the upper loft . the top angle will be 60 degrees with the bottom angle being 70....with this the middle angle will be 140.... my question withthese angles and the measurements i have listed , what would the board lengths be for the boards making up the trusses.....

thanks in advance

The lower chord is 5 ft. 10.5 in. The upper chord is 2 ft. 3 in.

I assumed a truss width of 12 ft and a truss height of 7 ft.(15 ft. minus 8 ft. walls.)

Lay this out on a template on the floor to verify.