Hi Chobonaut ,
I have a 350 also and it makes me sad to see this excellent camera lies on the shelf. I used the camera at the last days of Polaroid and some images terrible , some sunny day old stone facade buildings shots were matchless. If ı am not wrong 350 have a 3 element Cooke based lens called as Taylor Hobson triplet and I think it is the same lens with Rolleicord and later Rollei 35 Zeiss Triotar. I found the Triotar bw and color pictures are among the best I have ever seen. I saw a picture taken at the evening and the different colored areas are like cut with a razor , that sharp.
I think You and I can buy a Fuji film for its cassette and fill with paper negatives. I still dont know how to match lowest light meter 75 ASA ring selection to paper. I heard that wetting the negative paper and put on to the another paper and contact printing is a solution.
Other solution is to use a 120 kiev 88 back fitted to the back of the camera , I did not try and I dont know does it fit there or not but most practical solution.
If anyone share their insight , it is welcome ,
Best ,
Umut