Many people have modified old film housings to fit newer digital cameras. The camera must fit in the housing with the port aligned to the lens and no interference on any side. You need the ability to build new parts, particularly the base, in order to line up the camera in the housing. You're going to lose some functions because of buttons or levers that you just can't line up. I've seen a few who made most of the functions work, but had to turn the camera on before putting it in the housing because they couldn't line up the on/off switch. If you're skilled, clever and willing to compromise, you can make almost anything work to some extent. Or, you can look for a three or four year old last generation camera with a used housing and usually get it for 1/3-1/2 the new price. I've taken many better pictures with my old D300, now worth about $600 including housing, than with my D500 ($6K invested in addition to all my old ports, strobes, arms, etc.) New technology gets you improvements, but better skills will far exceed a better camera.
D500 NA-D500, D300 MDX-D300, 2X YS-D1, Tokina 10-17, Nikon 60AF D, Nikon 105mm AF-D, Nikon 35mm f2.0, L & M Sola 800/1200
Nikon F100 w/Sea & Sea NX100 Pro