is it worth it to rebuild a TBI engine with the factory heads? i know the stock heads are horrible but i dont have enough to swap them out yet. the motor has 170k on it and i want to rebuild. would it be a waste of money to use the stockers now and when i save up enough do a head swap? if i do use the stock heads what is the max lift i can go with on a cam? i really really want to rebuild it myself but i just want to make sure i dont go wasting money i dont have.