There's a guy on eBay who sells good used manuals for all such equipment. They come 2 days later. I don't see how you can loose with these pieces. Cutters only need good belts and tires. You can recondition the cutter bars yourself. Convert to bolted sections if rivets were used.
Baler is wire or twine? If twine, convert to plastic.
Just grease them up, pour old motor oil on the sickle bar and drive chains, roll them over slowly. Look on the New Holland website for parts & pictures.
Is the 495 a 12' mower? That usually drives a wider rake and a high capacity baler throat. The other mower is a 9' deal and more likely to go thru standard gates. I've liked using a 495 because the swing tongue allows you to a neater job in the field, especially in odd shaped fields. However, it can get confusing if you hurry thru a gate.
You can roll the baler over by hand. When it seems to be free, trip the knotter drive and watch it spin up. These machines were designed to run a tree thru them so you can't break them if the shear pins, friction brakes and retraction springs are properly spec'd.
What exactly have you got to loose?
Post some pictures and get some free estimates...