In order to go "post 70" on everything, how deep would I need to go? I know the water pump is different, and in turn the timing cover would be different as well. How much other stuff would I have to change?
You will need to replace the timing chain cover and water pump from the 67 318 with the one that came on the 73...
I would keep the 67 vibration damper on the engine, but the timing mark will be off... Just get a piston stop tool and find TDC and make a mark with paint or white out on the vibration damper to match the timing marks on the 73 timing chain cover...
Then you can use the 73 power steering setup and also use the 73 style alternator mounting brackets...
Now the water pump outlet for the lower radiator hose will match up with the one from the 73 and you can use the 73 lower radiator molded hose and stay away from the flex hoses...