Have done this single to-dbl t-chain conversion to my 82 380 sel. Also removed the heads and the valves to resurface everything. Probably did overkill overall, but I average 19-21mpg respectively. I run this car 75-80mph back-and-forth to work every day. Not much off the line, but it cruises when it gets on top as mentioned above. The car has 130k now and shows no sign of any failure since the 8k mi I put on it. les