So, assuming the cockpit window is the "standard candle" for absolute measurement. and Bandai's kit is accurately scaled as 1/72 and the MPC window is proportionally sized
The Bandai 1/72 comes in roughly at 2.2 to 2.3 cm
The MPC comes in at roughly 4.0 to 4.1 cm
So that means that scaling up from the "known" scale of Bandai, the MPC is between 1/38 and 1/39 scale
Again, assuming the cockpit window being the standard candle for size across all original trilogy TIEs, that makes the Studio Scale Model 1/38 or 1/39 scale.
If that is acceptable, as mentioned, simply build from a Bandai kit and it will be an exact donor for a 1/72 scale Tie Bomber
If, as mentioned above, you want the Studio Scale model to be 1/48 because the Tie Bomber should be larger than a standard tie and likewise, the cockpit window is larger, then as mentioned, you will need a donor kit that is in the 1/54 range
I could be wrong, but I believe most of the size issues stem from inconsistency in how large people thought the studio models were. I believe there was some old article where it was mentioned they were intended to be built to 1/16 scale, but had 1/24 figures in them since that was the closest size they had available. If you go with scaling off the studio models, and the studio TIEs being 1/16, then you get the Fine Molds Tie sizes. At some point that sentiment shifted and the whole ship was considered to be 1/24 scale. This was further championed by the FFG people researching the Tie scaling for the X-Wing mini game. The "official" numbers were revised and that results in the larger TIE that Bandai and FFG used.
Again, this is not necessarily fact, just info I had gathered and stored over the years. If am mistaken about that history, please let me know
Also I apologize if any of this comes off as argumentative, I am just searching for answers myself and it's a subject I love discussing, but sometimes it is hard to convey tone of voice in writing