This is my first post here it’s been a while since I’ve worked on my vehicle, but I figured I’d reach out for some input.  

I have a 1934 Chevy express    Which did run roughly when we first obtain it in the early 2000s    But my father wanted to upgrade the 1934 engine to one that was a little more modern     he obtains what I believe to be a 1945 GMC straight six   Out of a 1955 bus that was being scrapped  but unfortunately, he wasn’t able to get the transmission out in time so this has been a constant stop point because we were never able to figure it out as far as attaching      so I wanted to know if there was any advice in regards to a transmission to be able to allow this newer engine to fit into the 1934 body with minimal modifications     we previously thought that there might be an adapter plate to allow the original transmission to connect with the new bell housing, but was never able to find such a item

I’m trying to find the photo of when it was still on the engine stand, but with no success so far