RE: Frankie 5x5 - close grip chins enough for biceps?
Increasing the size of one particular muscle at a greater rate than the rest of your muscles or your overall bodyweight is not really feasible for the natural trainer. If you want to increase the size of your biceps, the best thing you can do is eat, lift heavy, and get plenty of rest.
For your biceps, I'd recommend you do whatever exercise gives you the best growth. Barbell curls, close grip underhand chins, or dumbbell curls are all good choices.
For close grip underhand chins, if you legs drift a little forward, it's not going to make a big difference.
Whatever you do, DO NOT add additional biceps exercises. If you are doing deadlifts, rows, chins, and curls, your biceps are getting plenty of stimulation. Adding any more exercises would likely retard your biceps growth.