Doug's headers not fitting - frustration
Looks like the engine is to close to the drivers side. Is the Centerline of your engine offset to the passenger side frame rail by 1.25”. The difference in measurement from the centerline of the crank to the each frame rail should be 2.5" total.
Ie; if it measures 16.25” from the Center to driver rail and 13.75" to the passenger side you're good. If it’s more or less than the required difference your engine isn’t centered properly. Adjust accordingly
Measure from Center of crank to inside of the frame rail.