Mine is a 1987 model, 58@28 and the sweet spot for me is 7 1/4". The info that came with my bow way back then (curved limb bed model) was the range for a 60" bow is 6 1/4" to 7", but in later years they increased the that to 7 1/2" on the flat limb models.
I would suggest you do what Fred Asbell recomended in his book. Take the brace height down until the bow vibrates and then start twisting it up until it smooths out. Fred said that would likly be the the best brace height. My bow will smooth out at about 6 3/4" to 7" but I get better arrow flight at the 7 1/4" so that is were I shoot it at.
Hope this helps.
DJ