Excellent collection , I have 350 and extremelly proud to own it. I dont know yours but mine have a glass Cooke Triplet lens and after trying it , I understood why there is always a Cooke Triplet at the databases of all Lens Design Softwares. It sees more detail than the eye sees on high frequency texture and It has a Zeiss Viewfinder. Such a big camera and extremelly strong stamped steel house , it gives me very big confidence to the camera. It has a sweet soft plastic cover and when I carry , I dont feel its weight. Coatings , aluminum , shutter release and the shutter noise is extremelly friendly. I will buy EFKE 4.5X3.5 Film this summer and develop with D23 and I have a sweeyheart. Thanks to a APUGer who sent me empty film canisters with paying 20 dollars to the air post.
May be you can convert one of them to 4X5. For cell , I use a circular big 3 volt lithium cell and it worked for 15 years and still goes strong.