Dave
I see you found something to spend your new found $100. This year I am also adding weight to my arrows. I am going with ST AXIS wraped blazed and 125 gr tip. I should finish up around 440-450 gr.

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.

Something to think about: You could use a 50 grain insert to increase the tip weight and really move your FOC up more towards the 15% range. That may change the spine that you need or maybe you could just add length to the arrow.

Bols , im shooting a 28 inch axis fmj arrow 340 spine with 125 grain muzzy's and love them they are fling great for me , Im shooting between 63-65 pounds .