To be honest with your budget I would just give it a full service, get a 4 branch and exhaust on for a better soundtrack and take it for a set up. Wouldn't bother taking the head off, having it worked and cammed etc etc. Not for the gains you will see. Unless you spend big bucks I don't think you'l get the power you hope for. Also sometimes people feel they need more power and never change gear over 4k rpm. Give the girl some proper revs and see how she feels!