First of all, you do not tell us where you are in the world, but I have some thoughts on your post here.
I could be wrong, but I'm tending to think, you have not done the required homework in your breed of choice, to be considering breeding. If you had, you would already be a member of the many Belgian associations and clubs and have built up knowledgeable friends in the breed. You would have a fair knowledge of the pedigrees in the breed, of the horse type you prefer and know who might own them.
Why do you prefer the 'farm' type? A quality Belgian is a quality Belgian, just as in any other breed.
In the US anyway, there are more Belgians than any other draft breed and this is why we find them constantly dumped in auctions. A friend of mine has rescued them for years. Hundreds unfortunately, end up as meat each year. They are also the first choice of the Amish for farm work.
You say you seek a sire with a 'squared off nose'. I presume you mean muzzle. While you might find such a sire, he will not necessarily produce it. This especially if bred to mares who do not display it.
Have you evaluated your mares, as to their possible breeding quality? If you purchased them from reputable breeders, one or other of them should be mentoring you, since you wish to become a breeder. You would probably not have to ask on an all-breed forum, such as this.
With the large number of Belgians around and so many going to auction, what will you offer the breed to make sure the foals you produce, do not end up in the same circumstances?
Will you be keeping them until old enough to be trained under saddle? Will you do the training, or have you a trainer in mind? Have you the experience in foaling and training, to become a knowledgeable breeder? Do you know the bloodlines of the breed, inside and out? Do you have a good knowledge of the problems, genetic and otherwise, found in drafts and particularly, Belgians? Have you the funds to be able to keep and train all the foals you might produce, until ready for sale? Have you already, well trained, top quality horses, to show prospective buyers? Have you shown the horses you presently own? If your foals do not sell easily, have you the funds to keep them, maybe for several years after they are trained, until the perfect home comes along?
Lots more to this breeding business than to advertise for a stud with a certain type muzzle and height.