The '70-'72 exhaust manifolds did have an open hole at the top of the choke tower on № 5 runner. That setup is problematic (exhaust leaks from a no-longer-available gasket, etc). All the new manifolds have the '73-up style of cast-in pocket at the top of the choke tower. Put on a № 1231 electric choke kit and you'll be all set with a better-than-factory, fully-adjustable choke.
Wise of you not to send in your original carb as a core; "remanufactured" carburetors are notoriously bad, but there's not much in the way of viable alternatives any more, so you're kind of stuck hoping and praying…and holding onto the original carburetor in case you will have to send it to someone qualified (such as Jon Hargrove at The Carburetor Shop) for a full refurbishment—the kind that goes well beyond what you can do at home with a carb kit.