a 69 camaro service manual should have the info how everything fits in place.I know there is more than enough info in the assembly manual that can help you. I used this service manual a few years back to get the vacuum hose's fitted on the rs headlight cannister's on my wife's 69 rs we did a while back. As Rybar suggested you will need to test fit and mock up parts as needed to check fit before drilling hole.The dse headlight kit will make it alittle less work not needing to replaced vacuum hose's when they split or crack and will open and close quicker.
Joe