Since your goal is to increase weight and get a higher FOC, definitely skip the wraps, and use feathers. Feathers are much lighter than vanes and they will make a significant difference in FOC. Don't be opposed to putting more weight on the front. An extra 20-30 grains will do almost nothing to your trajectory, but will make for a more stable arrow that has less tendency to deflect or plane. Plan this before you cut your arrows and you can easily get them to the length that allows for perfect spine.