Before you do the mod you will find that one of the concentric lines in the timing cover is the correct diameter to grind/ machine for the seal holder to fit. 1st time of doing this I accuratley marked out where the new hole should be, It fell where the pressed dia lay. After grinding it out it was rechecked and found to be within 0.005" of positional accuracy. As this is within the setting linits for the seal I called it close enough! It maintained this accuracy after TIG welding, Far more accurate than braising. Cheers for looking