A field cultivator 'here' works about as hard as a disk, and does the same job. In our clay, a disk is a bad thing, it packs the wet ground like a sheepsfoot packer, we all parked our disks in the 1970's and got field cultivators. They have meduim strength shanks, either spring loaded or S shaped springy type, with duck foot cultivator shovels of 5-9 inches on them (can have narrow 2 inch spike shovels, but rare).
A harrow is a light drag, some are wire spring type like jumbo siderake teeth, some are spike like the typical old horse drag/harrow. (Most field cultivators and some disks 'here' have a couple rows of 'harrow' teeth on the rear of them to level off the ground nicely.)
A chisel plow has very strong shanks that go into the ground as deep as a plow, and pull as hard as one, some are 2 inch wide bottoms, some are 3 or 4 inch twisted shovels. (Some chisel plows have a row or 2 of field cultivator shanks on the rear to level off the rough ground.)
I've seen imlements that are confusing between these 3, and hard for me to put in one or another classification as they seem to cross over.
In any case, the 20 foot harrow I have is a good match for a 45 hp tractor, the 25 foot one I have it often too big a load for a 45 hp tractor, so it would be hard, in my soils, to pull anything 32 feet wide with 60 hp, even a light harrow.
But it depends on soils, conditions, and what the implement actually is, and if it has a few harrow rows on the back of it.
In spring I can't hadly pull the 20 foot disk (the few times I use a disk any more) in fresh dirt. But in fall if I want to disk down some cornstalks in the firm dirt, the smaller tractor hardly knows the disk is back there.
Then the neighbors have come with a new type of disk, they have 400 hp pulling their 24 foot disk - it's a massive, huge bladed thing that works the soil deeper than a plow.
It's so hard to judge an implement with just a name to it, never sure exactly what it is we are talking about.
So this was a good thread, good question. Maybe the answers weren't so good. :)