I did the engine cradle upgrade, installed the new isomounts, and the new head gasket. I started the tractor today to see how things were working. The engine still smokes on start up and there's still a lot of engine vibration with the new mounts. At least it's the whole tractor shaking now and not just the engine on loose mounts. At this point, I'm not convinced that using Cub OEM isomounts are much better than using some cheaper after market mounts that are available. Maybe it will smooth out somewhat with more running. Some other articles I've read indicate that it will get better.
While I had it apart, I tried to repair some of the stress cracked sheet metal around the engine with my mig welder and ended up causing more damage than I repaired. Still a novice at welding on thin stuff and it Warped badly.
Old piece of sheet metal picture
I had some similar thickness sheet metal in my scrap pile so I tried making another piece and it seems to be working fine.
I also made a muffler crutch to help support the other end of the muffler
Muffler crutch installed
Looks like this project may have to be put on hold for awhile. I've been doing some re-modeling on our kitchen (building some new cabinets and some new cabinet fronts) and my wife wants me to get back to work on that.