C.J. is right, a Holley is a bit tempermental for street driving. You can tune it in just sweet one day and start it the next day and it just isn't quite right. HOWEVER! If you want speed then I'll take a Holley any day. C.J. they do make spreadbores. I have an 850 double pumper on a '69 455 sitting on top of an Edelbrock Torker intake. After doing all the math, it is right at 11.5:1 CR. Crane cam 572 lift 310 dur. Man is it fun! But no, if you try to drive it around town it will give you whiplash from all the bucking from the cam not smoothing out yet.
Kevin