1997 lawn Boy motor switch

I have a 19 gold series that I am trying to swap out the engine with another. The current engine has a plastic carburetor and a primer bulb, the new engine I located has a walbro carburetor with a manual choke. Everything was going great on the change until I noticed the difference in how the throttle cable hooks up. The old carburetor will fit on the new engine, but I noticed their is a port (circuit) between the carburetor and intake that the old engine and carburetor do not have. Any help is appreciated to help me finish this job