Welcome to the wonderful world of carpet farming Mark.
Scaledown have recently issued a 4 furrow Ransomes plough and I'm guessing it could be extended to 5 furrows. As Robbo mentioned, Sean is fettling his Ransomes/Pettit 8 tonners at the moment.
UH have made four versions of the Matador Gigant, maybe about 10 years ago. One in silver, two in the dark green and one in the lighter green. They are not easy to find, but they do turn up a couple of times a year.
https://www.farmmodeldatabase.com/en/view-details/011607/universal-hobbies-1-32-claas-matador-gigant.html
There's a long queue of people waiting for someone to make a massey 29 or 30 (or 500) seed drill. For such a popular machine it is strange that nobody has yet made a model of it.
Looking forward to seeing your diorama.