just got my heads back from the shop and will be putting my motor together in the next couple of days. i had to replace most of my valverain for the 73 cam going in. i planed to use the stock low hour timing chain and push rods on the motor since they are barely used and this is a budget build, are these things i should replace? the motor is gen 6 454 with factory roller cam, i dont think a regular double roller will fit the motor and i am not even sure i have ever seen a double roller for a gen 6? or if a double roller will clear the factory cover?