I run an 850 DP on the mild 440 in my 63 and it works very good. It has a nice clean idle and still launches great at the track with no stumble at all. It is basically a stock 850 with the choke blade removed and jetted up a tad. I also drilled the squirters a bit but thats it. In fact the last time I went to the track I ran on the same plugs that have been in it for a year. DP carbs work great on auto's as mine and my sons cars are both auto's and he uses a 750 DP on his Dart. Either carb will work on your street car with 3.55's but if you plan to race it some I would go with the DP. Ron