Hi Romulus, you have done the smart thing by asking experienced guys here first. There's much more to fitting a backhoe than just bolting it on or attaching the links. Stand back and take a minute to look at the tractor, the backhoe you intend fitting, and consider whether you have ever seen such a combination before. THEN .... look at other machines of that era and notice how much re-inforcing framing they have - this is important. The tractor, as great as it was for its time, was designed as an agricultural machine. Adding loaders and backhoes to them puts not just a huge amount of additional and overhanging weight, but unusual and unintended forces for which they were never intended to cope with, unless they were strengthened.
It would also help you to do a little looking at original earth-moving machinery - search for MF 20/30/40/50s with backhoes for sale - you will then understand what I'm saying. I have a MF40 industrial with only a loader, but its frame rails reach right to the rear axles. The whole machine overall is stronger and heavier - that's how MF built them.
No-one is saying you cannot do this, just don't overload it before you begin to work. One more point: If you opt for a 3PT mounted hoe, DON'T use the top link mount, use the triple-holes below it, on the transmission case. They are there for heavy implements and forces.
Feel free to upload some pics, and ask more questions ... we're an enthusiastic bunch!