Boiler room Ventilation question

So, as is usual, depending on who you ask and what day it is, I thought since it’s Thursday I would ask the Thursday crowd. Boiler room ventilation. I have a 600 cubic foot cinder block boiler room with a WM-65 input 250,000 BTU boiler and an A.O. Smith 75,100 BTU gas water heater. Plenty of room around all the appliances in the room. The DOB required that I tightly seal off every hole that every pipe created going through the cinder block boiler room walls which includes a self latching door. The room is now AIR TIGHT! Now, those gas appliances are having a really hard time breathing. What ever air that did get in there through the holes is now plugged and there is no direct to outside venting, never was and DOB did not make an issue of that fact (in the violation!). I want to correct this and I’m having trouble figuring out which formula to use to compute the duct size. 1 sq. in. per 1000 BTU appliance total, 1 sq. in. per 2000 BTU appliance total, 1 sq. in. per 4000 BTU’s appliance total? In my case it could be anywhere from 325 sq. in. of vent (and there is no way I even have that much free space on any exterior wall to accommodate) or 81.25 sq. in. which I might be able to do if I split that into two vents to the one boiler room. The boiler room is at the back of the house making that direction the shortest route for a vent. I would have easy access to the storm cellar double door egress area. There is fortunately a grated opening as part of the cellar door unit that is 9” X 34”. Could I utilize that in some way? I also have the standard unused old coal chute at the front of the house which is smaller in size, farther away from the boiler and has a metal door with vent. The rest of the cellar is open, total cellar area 18’ wide by 35’ deep x 7’ high. So thats 4,410 total cubic feet. I would rather have something installed instead of nothing there. I don’t want the boiler and water heater to take air from my sleeping kids! Any guidance is greatly appreciated. – thanks!