There is a standard formula that can be used as a starting point in your design. For a center fed, wire dipole, this formula is 468 / frequency in megahertz. You can cut the antenna a few inches longer which would allow me to trim the antenna in order to get your lowest S.W.R.
The inverted vee is about 2 - 5% shorter than a dipole at the same frequency. Use 3 or 4% as a constant in the calculation. You can change this value to any number that you like to use.