Since you are going with a 283 and not a big cube deep breather there is a quick and cheap solution to your problem. Use a 55 or 56 car 265 left exhaust manifold. It WILL CLEAR the steering box with the engine mounted in the middle and straight. There is a little "dip" in the manifold that will clear the inside upper corner of the box and the bolt in that corner. Have done probably a dozen for cruisers but not recommended for big cube big horsepower engines because the 265 is a flat log type manifold that doesn't flow near as well as rams horn but are fine for up to 225 or so horsepower. If side mount motor mounts you may have to tweak the drivers side mount as the exhaust pipe drops down between the first and second spark plug. No biggy. I see 265 manifolds at every swap meet I go to for about 20 bucks.
