Let's start with your desire to give up on the existing carburetor and buy a new one. The OEM carburetor is no longer available. The are two common reproductions currently available. The first is
assembled in the USA from multinational parts. It is rather expensive, but good quality. It typically works well right out of the box. The second one is assembled in China from China made parts. It is a little more than 1/10th the cost of the USA assembled carb on eBay. But, it can have issues out of the box. The float is frequently not set properly. Also, there have been issues with one of the air bleed holes not being drilled completely. Both of these issues are fixable by the average home mechanic. If you opt for a new carb, the choice is yours.
You say that you disassembled the carburetor, cleaned it and reassembled it. But, we don't know whether it had all the properly functioning parts and gaskets installed before you began. There is a brass part that is mounted into the carb top called an idle tube. It is easily broken and we don't know whether it in still intact. Perhaps you could post a photo of each of the two halves for us to look at.
If all is in order there, my suggestion would be to start simple, by adjusting the float in accordance with the diagram below. That adjustment is a trial and error process of slightly bending the float mount arm and/or the stop tab until you achieve the proper settings. The float drop dimension is 1.6 inches with the carb top positioned in the upright position. The float lift dimension is 1.4 inches with the top positioned in the upside down position. Maybe a little confusing, but give it a try. Then reassemble the carb, put it back on the manifold and try to start the tractor. There are further adjustments to be made. But, we can worry about that later.
Also, it wouldn't hurt to read through all the carburetor and fuel related posts in the How-To Forum before you start.
P.S. Note that the float dimensions are taken with the gasket NOT in place.