1975 dodge van not starting

Sorry if this isn’t the place to ask but the van was working a few weeks ago and just suddenly won’t start. The engine cranks when I turn the key but not getting any spark. There is an MSD ignition from the previous owner and as far as I can tell, everything works if we do the bypass test. We got spark with the plug grounded when we touched the purple and green wires together but when we hook everything back up, no spark on the plugs. Our best guess is something with the ignition as the housing is a little loose and turns when you turn the key. I

And sorry if any of this sounds odd or whatever. I know nothing about cars and the mechanic (father in law) was supposed to help me when I bought it a few years ago but flaked out. Now I gotta kinda learn everything at once lol. And the van is currently dead in the driveway being covered with snow.