That all depends on your skill as a bowyer...
66" should be a okay, if ya can make it. Thats the typical recommendation for 28" draw.
But
VM is amazing bow wood, 60" or 62" if ya know what your doing....
I just made one, 1 3/4 wide at the fade and just over 1/2" think. It is 58", flat bow style and ~60lbs at my draw 28.5"...
The bow is made from known tension wood. It has chrysled some and to my credit, very evenly. lol.
It is very fast but honestly is not long lived.
Whatever ya do, start thick an wide, creep up slow on you draw weight/length.
I have never made a VM over 62"... I dont have dimensions on any others over 60" at the moment...