For anyone that is interested, the swap went off without a hitch. Even the mule belt from the crank to deck worked. Everything lined up correctly. Having the 2 tractors side by side it was obvious they used the same frame/chassis.
Got it on and went for a test mow. The 46 deck is in sad shape. All 3 spindles are shot and all 3 blades are as dull as a baseball bat. So we didn't really cut grass, just beat it into submission.
That being said, it certainly put a work out on the 16 horse techumseh. I'm attributing that mostly to the worn spindles and dull blades.
Overall I'm satisfied, and will be more so after I give the deck some tlc.
Here are some pics I took.