I took a look at the 1650 and the 682. It appears the rear is clocked a little differently on the 682 than the 1650, which makes the drive line a little higher at the engine, which is why the special engine mount adapters are required. The other method would be to re-drill the front bolt holes on the frame where the hydro mounts the axle housing to the frame and use the front hydro braces from the 1650. In that case the engine mount adapters wouldn't be necessary.
Nevertheless, I took a good look at things and decided the 682 really needs a complete overhaul. It's not worth re-powering as it is and I don't have time to overhaul the tractor right now. Not that it's in bad shape, but it needs love I can't give right now.
So, the 682 is going to be on the block, either whole or parted out. I may wait until I get the 1650 finished, just in case I need parts from it for that project, but it will go eventually.
After shopping around and pricing a bit, I ended up buying a JD 425. Sorry guys, but it is exactly what I was looking for. Expensive, but I love the tractor. Couldn't find the Cub I wanted in the price range I needed.
The older, larger, better cubs are just not very plentiful around here, but JDs are a dime a dozen.
Thanks for all the willingness to help and the suggestions. In the end, I took the easy way out.