Quote: why not just get a mag318 core and use that
I agree, the 318 mag is a sweet little package that blows the doors off the older ones. Mileage is good as well, wife's 318 magnum Ramcharger knocks down 20 MPG on the road.
318 mag is a virtual bolt in, very easy swap, old engine mounts are there, transmission pattern is the same, sealing is greatly improved over the old engine.