Yikes! 16:1 with quick ratio idler and pitman arms on a manual box and wide tires? You sound like Hercules. Are Scheumaker Tri-Y's out of the question? I know they'll allow enough room for PS and quick ratio pitman/idler's; however, I think they're only good for about 500 hp or something.

http://www.engine-swaps.com/Pages/ProductsType/BRB_Headers.html