one thing, i've heard lot of people tried to make the snakedive roll good but it was impossible to get a good smooth roll. So i wonder what your going to make from it.
I am taking an educated guess, 100-120 ft., because the cobra loop is 135, and the snake dive comes after the loop and it taken at a decent pace. maybe even 90-110 ft.
The local town hall usually has copies of the blue prints for major constuction projects in the area, but I don't know if they'll let you copy them or even look at them.
^I don't know of any town halls that keep blue prints of construction projects. The only reason a city or town hall would have blueprints is if they are for a project funded by the government or the blueprints were submitted with an construction/building permit, in which case the blueprints would be returned to the builder after a permit is granted or denied.