Depending on where you live and the time of year you will be driving this engine may allow you to just block them off. Using an aftermarket gasket without X-over passage is an option.
This passage area as mentioned already allows hot exhaust gas to heat the fuel charge by keeping the floor if the intake right under the carb heated. This does help a cold running engine become more drivable until up to operating temp and feeds the gas to the EGR valve also dumping raw ex. gas into the intake fresh fuel charge BUT the down side is it is always heating the fuel charge and that is not good for power or mileage.
If you can either live with allowing engine to warm up before driving in cold country or pass any smog check without EGR function BLOCK that baby off with a solid gasket. Ex gas entering fresh fuel charge and hot gases under the carb are never good for performance and even worse when using an aluminum manifold as they xfer heat to fuel charge better anyway. If local laws allow then go for it.