I agree, the 424 is generations ahead on features. The post hole digging has been well covered, but let me add that for rototilling new ground, you need a really slow ground speed while keeping engine speed up for PTO power. A 9N/2N/8N does a really poor job, way too fast ground speed. If you go that route, get a plow and a 3-point disc.
An old Yanmar would have a slow ground speed, some have a super slow range, and the hydraulics are live. If you want to stay with domestic iron, there are quite a few options once you get past the early 50's.
BTW, just because the guy with the 424 won't come down on price does not mean it is a bad deal. If he raised the price $400 and then gave you $400 off it would feel better though, we all want discounts.
PS, a tractor with a new crank worries me a little. What else was wrong, what else was done to it?