Those will cut better! I flipped my over (no hole in deck access cover, not crawling under any bush hog to sharpen blades) and had to take the carrier off with a 15ton puller and torch. Sharpened the blades, which are just about as bad as your father in law's, and they will get me thru the summer. I'm just not ready to fork over the $260. I'll wait and see if someone else has an alternative.
I've got to move on to finding RSA plates for my 4600 Deere to put my 48 Backhoe on, another thread. Good luck, stay safe and have a great summer.
PS> If he doesn't have one get him an overrun coupler, runs about $60 but sure makes life easier and safer for the old tractors.