Older Fireplace Help

[Milma]

Hi. My wife insisted on having this “mid century modern” fireplace that is similar to the Malm. Unfortunately, the stove outlet is 6.36”-6.5” ID (it is slightly warped). It came with 48” of pipe already assembled together with a damper. The opening on one end of the pipe is 7” and 6 7/8” on the other end. The 7” end can fit over the opening, but from what I understand it needs to go *in* the outlet. The other side will not go in or over. I feel like there is a missing piece that once connected the outlet to the pipe.

We would like to use the existing pipe if possible, but have considered having to use new black stove pipe. Either way we need to figure out how connect it properly to the stove outlet.

Anyone have any ideas?
Thanks.