I have hooker super comp headers on my 68. They slide in and out no problem and have clearance to get the oil filter on and off. But do not know what year they were made and if the new ones are made exactly like mine.
I have a friend with a 69 bird and he has Doug's. I had to modify his drivers side header and move one of the tubes because his Pittman arm was hitting the header tube and preventing full steering turning.