Nick, if you squint when you're looking into the future, you'll see a really cool, really rare hotrod motor. But, if you open your eyes wider and look into the near future, you'll see what trouble a 'white elephant' is. Those Caddies will be hard to get parts for like the flywheel, clutch, transmission, oil pan, and water pump.
I am trying to whip a 'white elephant' into shape right now and it's a struggle. I have acquired a Lincoln 'Y' block with no flywheel, starter, or clutch. There are two bellhousing options; both not very good. I can take an 'FE' bellhousing and machine the bolt holes and dowel pin holes to fit on the 'y' block or take a big truck 'Lincoln 'Y' block bellhousing that is almost 2 in' too deep and get a long snout input shaft to go though the bell to the rear of the crank. It looks like I will have to get a starter that I can clock about 30* to fit in the casting of the motor. Boy, am I ever going to have a rare motor though.