There are quite a number of people who have that intake and have had them perform really well. Re the original question the hole is as Tom S first said is there for the air choke. It is ineffectual in that it runs vertically from under the intake straight up to the top where it is shown in the picture - for only an inch or a tad more than that. That is waaaaay too short to get heated air to the choke and make it operate correctly. Factory intakes had a steel tube that fed the heat choke and it ran inside the crossover all the way across to the driver's side, and back, before feeding hot air to the choke. When putting dual quads on the offy intake you need to install an electric choke on the rear carb - or a manual choke. You do not need to plug that hole if it isn't used however since it does nothing.
There are several brands of electric choke on ebay and they all work. Here is the Jegs version.
https://www.ebay.com/itm/Quick-Fuel-...MAAOSwN3ddb37B