Thanks Rick, I believe a 605 made its day view on low cost G bodies like the 1978 Malibu. Most I have seem have had the optional Saginaw. A far as clearance goes I don't understand I have headers on the 396 in my 55 with a CCP500. Yes its tight, but its a BBC. As far as Cnuts chart goes he must have cut and pasted that from somewhere, that missed an important point. The early 800 Boxes were junk, example the one on my 67 SS 350 had no road feel, the one bolted in place from a 77 Z28 with variable ratio was wonderful. I had similar results on my 70 Chevelle SS 454 using a later Trans Am box.
Found this explains my results. http://www.hotrod.com/how-to/chassis...g-box-upgrade/