In your scenario, if you can make the body (by grinding its interface) and back fit together, you can then just use the flash sync cable. With Phase P45+, I can use the flash synch cable (with an activation wake up button) and capture photos within 1/30. But my Hartblei got some shutter movement issue, so I had the shutter totally removed. I am not sure if it is going to work directly with the e shutter on CFV 100c - I can push the mirror lockup to have the clear light path. My current plan is to just use some in-front-of lens 3D print shutter and experiment with the old CCD back. The Arduino / ESP 32 S3 is very powerful because it can wake up the back and then make the exposure, trigger the flash etc in a pre-defined program sequence.