For a recurve, start at 7 1/2 inches. Tighten the string a few twists at a time till you find the quietest brace height. If that doesn't seem to be working, drop back down to 7 1/2 and lower the brace a few twists at a time. I very seriously doubt your brace height will be less than 7". Contact just about any string maker or bowyer and they'll be able to help you out best.
I can't ever remember the measurement rule. One is 4", the other is 3"; longbow versus recurve... I just call my buddy in Georgia and he builds me another one.
