Casey, Did Advance Adapters realize it was the original cast iron bell and not an aluminum one? I would think that it would be fine although, I was planning on the same thing in mine one of these days.
The cast iron bell will hold an SM465 with no issues. It is 40# more than the SM420. (ranger weighs 80#).
Also, on the 4wd, did they hang a transfer case off the back of the tranny as well? Did they use another mount on the transfer case?