318/XE262/#302 heads and what stall converter/rear end

Hi all, I recently upgraded my stock 318 with #302 heads, milled down .30, valves cut back, 3 angle valve job and all the ports matched with some minor bowl work done. In addition I installed the Comp XE262. Other than that I'm running a set of Dougs headers, Eddie performer intake and a 600cfm carb. I'm running a stock 904 tranny and have no idea what my rear end is. Whatever they ran in 73 darts with /6 set ups..

Once all together I've noticed the drive-ability is lets say off.. It idles rough and I'm finding it I have to double peddle or put the car in neutral at stop lights. Not sure if this is from the cam/stock stall converter combo? Since this is my first real engine upgrade and I'm not sure what to expect so any feedback from you mopar pros would be greatly appreciated. While I'm at it I was hoping to get any feed back on what rear end to run.