My daughter had a Cherokee that had a growl in it. I changed the rear wheel bearings that were definitely bad but it still had a growl that sounded like the rear end. It wasn't. it turned out to be the drive shaft. It was that funky CV joint type coupling.
This may sound dumb, and I'm not familiar with the bolt pattern, could you install the manifold up side down? Then you could use an elbow to exit the exhaust to where you have room for it.
Congrats!! Don't feel bad, My buddy Scott that I sold the 49 p/u to was a great grand dad at 58. I also have a friend that became a dad for the first time at 54. I think I would rather be in the Grandfather territory.
Nice score. On my trailer the tail lights are housed in 3/8" wall rectangle tubing with a window cut in facing rear for the lens. Haven't knock any off in 15 years. I will try to get pics later.