im building a 4.5" sfbd/traditional On 18s with a 350. The 350 wasnt too bad, as far as fabrication.. the enine mounts lined up almost perfect to the frame mounts. And all i had to do was cut up an old 4 link to make my frame mounts.
with the 4.5" bodydrop theres absolutely no way its going to fit under the hood. If you look at the valve covers in reltaion to my tires, they are almost as tall as my tires.. Now right now, my tires are 225/40/18s.. And they are about 1" out of the fenders. so the valve covers will probly be damn close to touching the hood. And the carb and intake manifold will stick out the hood. With as big a bodydrop as i have, i doubt you could even get a fuel injection system with a low enough profile to clear the hood.