Well Steve, I can say that the engine does have the right style oil pan, so you're good there. I also see a fuel pump on the side, which isn't needed for a Cub Cadet, so you'd probably need to remove it and find a block-off plate.
As for paint, I would say leave the cylinder head unpainted for maximum cooling, and paint the cooling fins around the cylinder with a high-heat black paint. Then the rest of the block, shrouds, heat shield, etc can be Cub yellow. I don't know specific brands but everyone has their own favorite and least favorite.
I see a few problems but you are smart and will overcome them.
You will have to extend the dipstick as it will be hiding behind the SG.
You have no mounting hole for the SG adjusting bracket.
I have seen many K241 engines with the K301 casted in them, are you sure it is a K301?
I cannot see the bottom of the pan, does it have the deep sump on it?
Steve - as Lewis implied, that "K301" casting on the side of the block doesn't mean it's a 12hp K301. I've heard that you can find that K301 casting on just about any of the Kohler K-series blocks. You've really got to measure the bore to see what you have.
Pan don't look right and WTH is that fan and screen all about??
I think I would have left it well enough alone.
Hope you don't have a boat anchor there.
My guess is machine work will run you about $150-200 depending on what is done.