Götz Special Run
Though it would take a bit of explaining, it is possible to show the chestnut roan G1 Morgan Stallion as a purebred Morgan. Though roan is allowed by the American Morgan Horse Association, it appears only two examples of the colour remain in the breed: a 1987 gelding and a 1985 mare, both of whom are highly unlikely to pass that gene along to the next generation. For more information on Roan in the Morgan breed, check out Morgan Colors (scroll down a bit).
Of course, you could make him a Morgan part-bred with a cross to a breed with current roan breeding stock, or you could show him as a historical Morgan which would require a little explanation card for the judge with a brief summary of his bloodlines and birth date.
For pedigree purposes, if you want a purebred, you could go one of two routes. First, you could make him an older model, possibly a sibling of the 1980s horses if you don't want to go back too far, or make him non-aging and have him born during a time when roans were more prevalent in the breed. If you want him to be born in more recent years, you could make him some paper parents.
In pedigree assignment, when a person wants to bring forward a particular extinct colour or bloodline from a historical horse, they will create a series of fictional progeny from that source containing the desired traits for however many generations they need to provide a parent or parents for their model. In this way you could have a 2014 foal with Viv LaMae, the 1985 bay roan mare (the dam of my 1999 roan stallion up there) as the grand-dam, or you could start with Doll Rose the 1964 dam of the 1987 gelding and create a fictional 1974 foal, 1980 grand foal, 1988 great-grand foal, a 1998 great-great-grand foal, which could be the parent of your 2014 foal.
Sure, it can take a bit of work and research, but it's a great way to learn more about genetics and your breed of choice.