nice cab coogan, the older grain trucks are still around and some of them are in excellent shape. i like the 90 deg z idea better than the 45 as it is so much easier to get the angle . when i bult my bucket frame i put a 13 inch rear 90 degree kickup and fish plated the inside plate top to bottom with a plate where it could not be seen.
briansversion of the front frame bacing would look really good .
good luck with the project