V Frame angle
My 36" V frame has something like a 27 degree angle. It kind of depends on how you measure it. Different reference points produce different measurements.
60 degrees sounds really large. You might want a large angle if you are building a V frame for a 26" or 29" wheel. For a 36" you would probably want a smaller angle. The reason being that a smaller angle on a large wheel will get the handle bars just as far in front of the seat (in centimeters/inches) as will a larger angle on a smaller wheel.
One thing you could do is try and decide roughly how far forward you want your handle bars to be and then pick an angle that will allow you to achieve that. Then design handle bars that are adjustable so that you can fine tune their position.
Of course, knowing where you will want to put your hands and therefore handle bars is not an easy question to answer without actually trying out a uni with an existing handle bar set up. Make good use of your neighboring unicyclists.
Geoff