Motor issues.

Okay first of all I'm not telling you what to do I'm just going to share my experience with what I did and you can take it for what it's worth.,
I've always set my lash cold so don't burn myself and get hot oil all over everything. When I have iron heads I set the lash about .003 loose and when I put aluminum heads on .006 tight.. it's just a nature of the beach how things work when warmed up... My cams are usually about .020-.022 lash and is the above differences when cold.,. That should be sick before you even start the motor...
With my high performance engines and even performance engines they like a lot of initial timing and that's in the 18 to 22°. But that said generally don't want to go over 34. So your timing mechanical curve should be around 14 to 16° of total mechanical.... Personally I don't use vacuum advance and that's just me not telling people what to do., Also I generally put the second to the lightest friends in so the ramps up pretty fast..
As far as the carburetors I did a lot of studying on this and one thing that popped up was if you look at Edelbrock carburetors that are sold as dual quads the carburetors are set up slightly different instead of exactly the same as you would think...
He might find one that has a smaller Jack or a larger Jack or smaller or larger metering rod or different springs as compared to the other one....
Of course this is all for Street performance and throttle response as opposed to just matting it to the floor at the drag strip and wanting both carburetors running exactly the same...
Again of course this is just what I do with my stuff and I'm not going to argue with people whether it's wrong or whether it right or any of that stuff it's just the way I do things not telling you what to do...