Jpeg is abhorrent for basically any large format project. If your not using a vector based artwork, at least save it in PDF or PNG. NEVER SAVE IT AT TIFF OR JPEG, OR BMP. You basically are playing with fire.
If your original source material is scanned images of jpegs, then you still benefit from a pdf or png because it can be stretched to your size and it wont turn into crap.
The size of the file is not revelant, 4.7 GB would be the upper limit so it fits on a DVD, the file can be uploaded on dropbox so the size is not an issue.
Also,the source file may or not be Jpeg. The Tiff file that’s presented in a link is just what its saved as. The creator of that file may someday show up here and give is a pdf or something. My copy of Amblizi file is a Tiff, not a jpeg anyway. A Tiff is a raster based using RGB colors, while i only work with CYMK which is superior for this application, so that conversion sorta messes with the colors of the OOB board. I think a TIFF does not really mess with pictures if they are stretched or shrunk. The problem i see is when the printer stretched the TIff file, something was lost and i think it was the crispness of the image but very minor.