73 Tuning issues

[RaysK20]

I dropped in a new good wrench 275 horse 350 in my 73. In the process I added a edelbrock performer intake and hedman headers and a new HEI to be rid of the points. Other then that the motor is stock. I also added a kit to the stock quadrajet carb to freshen it up. It had been sitting for several years. It fired up real easy and I broke in the cam for 30 minutes. I set the initial timing at 10 degrees btdc. off the vac. It stumbles real bad just off idle and or will bark threw the carb like the timing is retarded, then runs like hell to about 5000 rpm. I have check rechecked then checked another ten times that my timing is in line with the marks and the distributor is lined up properly. I cant find any vac leaks anyplace and it idles smooth as glass. I am at a loss. Should I dump the quad and go buy a new edelbrock carb? Any help would be great.