Some set ups very similar to yours prefer ported vacuum. in fact I believe edelbrocks tuning tips state thats the most common unless you have power brakes. But there is nothing wrong with using manifold vacuum if your car runs better that way. Also, I have a lot of experienced people around me that all like to unplug the vacuum advance and use real light springs in there distributor to have timing all in as early as they can. granted they are performance junkies and not driving there cars concerned about mileage.
Im not stating the advice already givin to you is incorrect, im simply verifying that that theres many ways to go.
I would suggest pulling the carb and making sure your set to spec, and hooking up an afr gauge to make sure your safe there. I had the 1407 carb on my 355 and had to tune almost every aspect of the carb, but I think that every carb should have this done. sometimes you get lucky and it runs but most likely it could be better. Even new carbs say to open them up and look for flash, or check floats n butterflies for proper position. Remember that its just regular people putting these things together. (maybe not every carb company but for the most part). and people get stuff wrong all the time. Anyway, Im not familiar with the 1400, perhaps its a good cfm size, I heard you mention alcky so thats probly why.
I now have a demon 750 duel inlet now and chose to start off going through it and making changes right away. then bolting it up, (my timing already set, youll have to do this), then checking pressure(edies like 4.5 but If you are running mixed alcky or straight, youll have to find out, then set your idle, then fuel air screws evenlyleaving your starting point of one and a half turns out. Then your idle again, then fuel air again, then idle again. all while its warmed up and of coarse with a vacuum guage, and timing gun all correctly hooked up.
usually guys will adjust the pump shot by moving the linkage from one of three holes. depending on whether you have a bog or not from stop will prolly dictate where you put this. also the electric choke you will want to adjust according to the whether. I was able to only have to move mine about twice a year on a perfect year but the weather around me now jumps back and forth and its annoying when the choke runs longer than it should.
anyway, I hope I was able to help you out. If you just try to remember the order in which they are performed to get the correct set up, then actually performing the steps wont seem like such a big deal. Once you have it down you will be doing it multiple times a season and doing so in just minuts.