I have more questions than answers to this:

An old Deardorff is too expensive, so you consider buing new? While I agree Deardorffs are overpriced, there are other used cameras that are not. After all, a camera is only a dark spacer between lens and film.

"300-360mm barrel lenses" is a vague term. That can be anything from a 305mm G-Claron which any camera can handle to a 360mm f:3.2 Petzval monster - where it might be better to mount the lens on a tripod and hang the camera off he back of it. Even a 360mm f:5.6 Symmar will tax many cameras. My Gandolfi handles it well, but anything less sturdy might struggle a bit.