What do you guys suggest

My concern is if you go smaller on a Farmall you will gain nothing. 300 or 350 will have less power, yet be the same speeds and dimensions as the 400. Go smaller than that and your into transmission driven pto. and still too much speed.

The very best tractor for you with that tiller is something like a B-275, 414, 434, 444, MF 35 or 135 or a Ford, Oliver 550, make sure you get live pto for that tiller. Those tractors all have factory 3 point with draft control as well as dual range transmissions with 2 gears that are slower than your 400 in number 1. These little tractors will also give great manuverability in a yard situation.

Don't even look at 300 or 350 utility, same speeds basically as Farmall. Farmalls were engineered to work best at speeds between 3 and 7 mph, and that is not tiller work.

I remember in the late 50s, my dad was looking at a 3rd tractor. He already had a H and a 300. He came home one evening, had been pricing new tractors. A Farmall 230 was only $200. more than the 130, around $1,800. as I recall. He first thought for the price difference, he may as well have the larger tractor. Then he decided 230 would be close to same dimensions as the H and 300, wouldn't be anymore manuverable. Probably not as good as the 230 was wide front and H and 300 were narrow front tracrors. Finally he decided 130 was the best buy as his main reason for buying was a smaller tractor for those light and tight quarters little jobs.

The 300 or 350 Utility tractors might be more to your liking. I'm attaching a link to a picture I found Googling. I have no idea where or when it was taken, but its a reasonably good pic of a 350U.

I saw a 560 rear frame in the YT "Photo Ads" several days ago. It is probably still there.

Then I would look for a Super A.