Timing mark

If you are returning the car to 70 spec....

You need
  1. 1970 up front accessory brackets
  2. 1970 up aluminum water pump
  3. 1970 up timing cover
  4. 1970 up balancer (or make your own slot at TDC on the driver's side timing mark, the 69 down timing mark will not line up on the 70 up cover on any cylinder. (I have that setup on my 67 273)
  5. 1970 up rad with passenger side lower radiator hose (70 up rads are kind of boxy compared to 69 down)
Add crank and water pump pulleys to the list too. The whole front end of the engine changed between '69 and '70.