i'll measure my Atomik Fuse for you tomorrow if you want
but yeah, the wheelbase plus about 430mms will be the length from front edge of front tyre to rear edge of rear tyre
wheelbase is where the tyres touch the ground, add on half a rear rim 152mm, and tyre about 50mm
then add half the front rim about 177mm and tyre 50mm
for the front section,
i work out where i want to have the diagonal section at the front of the rail/guide
cut the sides down to the flat bottom section, then spread them a little and fold the front up at a 45°,
then just weld the overlapped parts together down near the fold
and don't forget to wire brush the galv off first too, or it'll be a messy weld