Joe,

What a lovely old tractor and don't be put off by what you have seen under the valve cover, it is amazing how much damage those small mice can do and their urine is so corrosive, but I am sure you have parts in your junk pile to soon put new valve gear back onto the tractor, I bet the bottom end crank and bearings is in good shape. It is amazing how those creatures work their way through such a small hole and build such detailed nests, bet there has been many families raised under that old 25 valve cover.

The styled 25 which is currently under surgery here in Lincolnshire has a manifold exhaust elbow which looks like new, that was one of the factors which took my eye when it was standing in the MN salvage yard, when I took off the hand holes the crank and big ends had so many shims in place which is always a good sign.

Here is a photo of the freeing off procedure